feat: add KeyMap with defaults and INI overrides

Maps key sequences to action name strings, with hardcoded vim-style
defaults and QSettings-based [keys] overrides. Unknown actions and
unparseable sequences are collected as warnings rather than treated
as fatal, so a typo in the config cannot silently misbind or crash.

Note: QKeySequence::fromString() on Qt 6.11 does not return an empty
sequence for unparseable input (e.g. "NotAKey++") -- it returns a
non-empty sequence whose toString() is empty. Detection uses that
instead of isEmpty().

1 files changed, 0 insertions, 3 deletions

diff --git a/src/main_placeholder.cpp b/src/main_placeholder.cpp
deleted file mode 100644
index 9ddb3f2..0000000
--- a/src/main_placeholder.cpp
+++ /dev/null
@@ -1,3 +0,0 @@
-// Placeholder so the library target has a source file before real code lands.
-// Removed in Task 2.
-namespace { int qtmaildir_placeholder = 0; }