refactor: unify card no-data face and fluid sizing

Extract card.notice so every cached card's no-data state is one fluid,
theme-consistent face instead of a copy per widget, and delete the
fixed-size card.label it replaces.

Derive weather's arc geometry from its band (pad, curve room, sun dot,
time labels) instead of fixed pixels, and cap the arc at a proportion of
the card's width rather than 240px.

Derive disks' bar-fallback height and its address type from the card's
own label scale.

Standardise the big-value factor to 1.0 across the fit_unit cards and
document the big-value colour rule and the disks headline exception.

1 files changed, 4 insertions, 2 deletions

diff --git a/README.md b/README.md
index 5ec6b61..2269a70 100644
--- a/README.md
+++ b/README.md
@@ -260,8 +260,10 @@ carries the primitives it should use rather than reaching for Cairo directly:
 - `card(cr, rect, colors)` draws the rounded card and returns the padded inner
   rect to lay out against.
 - `font(cr, family, size, bold)` and `rgba(cr, colour)` set the state.
-- `text(cr, x, y, s)` draws at a baseline, `text_right(cr, x, y, s)` aligns to a
-  right edge, `label(cr, x, y, s, colors)` draws a small-caps section label.
+- `text(cr, x, y, s)` draws at a baseline and `text_right(cr, x, y, s)` aligns
+  to a right edge.
+- `notice(cr, inner, colors, title, note, hint)` draws the no-data face every
+  cached card shares when its sampler has not run.
 - `measure(cr, s)` returns the **ink** size, what the glyphs actually cover. Use
   it to centre or right-align.
 - `advance(cr, s)` returns the **x_advance**, how far the cursor moves after