build: bundle the fonts the placeholder pane will need

Groundwork for item 30, the blank right pane. Nothing references these
yet; the pane itself is the next piece of work.

The pane is drawn from the user's own HTML mockup, which sets its
wordmark in Oxanium and its text in IBM Plex Sans and pulls both from
Google Fonts. That @import cannot work here: the web view's interceptor
blocks every request by default, deliberately, and neither font is
installed on the development machine either. Shipping them is what
makes the pane look the same on every machine.

Both are SIL OFL 1.1, which permits redistribution and is compatible
with the GPL, and each carries its licence text beside it. The README
records the pairing.

Both are subsets, since they are embedded into the rendered document as
data URIs and the full families would dwarf the page using them.
Oxanium is instanced to weight 800 and cut to the nine characters of
the wordmark: 43K to 1.2K. IBM Plex Sans is cut to Latin-1 plus common
punctuation rather than to the exact strings in use: 525K to 13K. The
wider cut is deliberate, because that font carries interface text that
will change, and a subset matching only today's wording would break
silently the moment a string is edited. Coverage of both was verified
against the strings they have to draw.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

5 files changed, 214 insertions, 0 deletions

diff --git a/README.md b/README.md
index 060e702..13002d8 100644
--- a/README.md
+++ b/README.md
@@ -449,6 +449,34 @@ strangers, and it is treated that way.
 
 GPL-2.0-only. See `LICENSE` for the full text.
 
+### Bundled fonts
+
+Two fonts are bundled under `assets/fonts/`, both licensed **SIL Open Font
+License 1.1**, which is compatible with the GPL and permits redistribution.
+Each ships with its own licence text beside it.
+
+| Font | Used for | Licence |
+|------|----------|---------|
+| Oxanium ExtraBold | the `qtMailDir` wordmark | `assets/fonts/OFL-Oxanium.txt` |
+| IBM Plex Sans Regular | the placeholder pane's text | `assets/fonts/OFL-IBMPlexSans.txt` |
+
+Both are **subsets**, not the complete fonts, because they are embedded into a
+rendered document as data URIs and the whole family would be far larger than
+the page using it. Oxanium is instanced to weight 800 and cut to the nine
+characters of the wordmark, 43K down to 1.2K. IBM Plex Sans is cut to Latin-1
+plus common punctuation rather than to the exact strings in use, 525K down to
+13K: it carries interface text that will change, and a subset matching only
+today's wording would break the moment a string is edited.
+
+To regenerate either after changing what is drawn:
+
+```bash
+fonttools varLib.instancer Oxanium[wght].ttf wght=800 -o Oxanium-800.ttf
+pyftsubset Oxanium-800.ttf --text="qtMailDir" --flavor=woff2 \
+    --layout-features='' --desubroutinize \
+    --output-file=assets/fonts/Oxanium-ExtraBold-subset.woff2
+```
+
 ## Development Approach
 
 This project is developed using AI-assisted tools. Code is generated with the help of AI based on human-provided specifications, design decisions, and iterative feedback.
diff --git a/assets/fonts/IBMPlexSans-Regular-subset.woff2 b/assets/fonts/IBMPlexSans-Regular-subset.woff2
new file mode 100644
index 0000000..ad23afd
--- /dev/null
+++ b/assets/fonts/IBMPlexSans-Regular-subset.woff2
diff --git a/assets/fonts/OFL-IBMPlexSans.txt b/assets/fonts/OFL-IBMPlexSans.txt
new file mode 100644
index 0000000..c35c4c6
--- /dev/null
+++ b/assets/fonts/OFL-IBMPlexSans.txt
@@ -0,0 +1,93 @@
+Copyright © 2017 IBM Corp. with Reserved Font Name "Plex"

+

+This Font Software is licensed under the SIL Open Font License, Version 1.1.

+

+This license is copied below, and is also available with a FAQ at: http://scripts.sil.org/OFL

+

+

+-----------------------------------------------------------

+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007

+-----------------------------------------------------------

+

+PREAMBLE

+The goals of the Open Font License (OFL) are to stimulate worldwide

+development of collaborative font projects, to support the font creation

+efforts of academic and linguistic communities, and to provide a free and

+open framework in which fonts may be shared and improved in partnership

+with others.

+

+The OFL allows the licensed fonts to be used, studied, modified and

+redistributed freely as long as they are not sold by themselves. The

+fonts, including any derivative works, can be bundled, embedded, 

+redistributed and/or sold with any software provided that any reserved

+names are not used by derivative works. The fonts and derivatives,

+however, cannot be released under any other type of license. The

+requirement for fonts to remain under this license does not apply

+to any document created using the fonts or their derivatives.

+

+DEFINITIONS

+"Font Software" refers to the set of files released by the Copyright

+Holder(s) under this license and clearly marked as such. This may

+include source files, build scripts and documentation.

+

+"Reserved Font Name" refers to any names specified as such after the

+copyright statement(s).

+

+"Original Version" refers to the collection of Font Software components as

+distributed by the Copyright Holder(s).

+

+"Modified Version" refers to any derivative made by adding to, deleting,

+or substituting -- in part or in whole -- any of the components of the

+Original Version, by changing formats or by porting the Font Software to a

+new environment.

+

+"Author" refers to any designer, engineer, programmer, technical

+writer or other person who contributed to the Font Software.

+

+PERMISSION & CONDITIONS

+Permission is hereby granted, free of charge, to any person obtaining

+a copy of the Font Software, to use, study, copy, merge, embed, modify,

+redistribute, and sell modified and unmodified copies of the Font

+Software, subject to the following conditions:

+

+1) Neither the Font Software nor any of its individual components,

+in Original or Modified Versions, may be sold by itself.

+

+2) Original or Modified Versions of the Font Software may be bundled,

+redistributed and/or sold with any software, provided that each copy

+contains the above copyright notice and this license. These can be

+included either as stand-alone text files, human-readable headers or

+in the appropriate machine-readable metadata fields within text or

+binary files as long as those fields can be easily viewed by the user.

+

+3) No Modified Version of the Font Software may use the Reserved Font

+Name(s) unless explicit written permission is granted by the corresponding

+Copyright Holder. This restriction only applies to the primary font name as

+presented to the users.

+

+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font

+Software shall not be used to promote, endorse or advertise any

+Modified Version, except to acknowledge the contribution(s) of the

+Copyright Holder(s) and the Author(s) or with their explicit written

+permission.

+

+5) The Font Software, modified or unmodified, in part or in whole,

+must be distributed entirely under this license, and must not be

+distributed under any other license. The requirement for fonts to

+remain under this license does not apply to any document created

+using the Font Software.

+

+TERMINATION

+This license becomes null and void if any of the above conditions are

+not met.

+

+DISCLAIMER

+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF

+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT

+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE

+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,

+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL

+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM

+OTHER DEALINGS IN THE FONT SOFTWARE.

diff --git a/assets/fonts/OFL-Oxanium.txt b/assets/fonts/OFL-Oxanium.txt
new file mode 100644
index 0000000..38913c0
--- /dev/null
+++ b/assets/fonts/OFL-Oxanium.txt
@@ -0,0 +1,93 @@
+Copyright 2019 The Oxanium Project Authors (https://github.com/sevmeyer/oxanium)
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+https://scripts.sil.org/OFL
+
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded,
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components as
+distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting -- in part or in whole -- any of the components of the
+Original Version, by changing formats or by porting the Font Software to a
+new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the corresponding
+Copyright Holder. This restriction only applies to the primary font name as
+presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.
diff --git a/assets/fonts/Oxanium-ExtraBold-subset.woff2 b/assets/fonts/Oxanium-ExtraBold-subset.woff2
new file mode 100644
index 0000000..96c821d
--- /dev/null
+++ b/assets/fonts/Oxanium-ExtraBold-subset.woff2