feat: add Character Map (charmap) MTK app

A standalone Window Server app for browsing curated sets of characters
and copying them to the clipboard for pasting into other apps.

- Four sets (Latin, Punctuation, Currency, Symbols) shown as a responsive,
  scrollable tile grid with category tabs, a live preview/detail footer,
  and a Copy button.
- Click a tile (or use arrow keys + Enter/Space) to select and copy; a
  transient toast confirms the copy. Mouse wheel scrolls; Tab cycles sets.
- Styled with the MTK theme (accent, surfaces, rounded tiles) to match the
  other Montauk apps, modeled on the calculator app.

The character set is deliberately the single-byte Windows-1252 range the
system font can render (the glyph cache only holds codepoints 0-255).
Copying writes the raw byte, so glyphs render identically here and in every
other single-byte-text Montauk app (copying UTF-8 would render as mojibake).

Registered in programs/GNUmakefile and scripts/install_apps.sh alongside
calculator; menu category "Applications", icon accessories-character-map.svg.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

programs/src/charmap/manifest.toml

@@ -0,0 +1,11 @@
+[app]
+name = "Character Map"
+binary = "charmap.elf"
+icon = "accessories-character-map.svg"
+
+[menu]
+category = "Applications"
+visible = true
+
+[launch]
+pass_home_dir = false