style(icon): regenerate F-Droid icon.png to match launcher exactly

Re-render both locale catalog icons (512x512) from the same logo as the
Android adaptive launcher icon, baking in the foreground group transform
(scale 0.5, pivot 114,108, translate 2,8) over the slate background so the
F-Droid render is pixel-faithful to the on-device icon.

Add design/icon/calendula_launcher.svg as the composed full-bleed source
of truth for store/F-Droid renders.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.2.1] — 2026-06-09
+
+### Changed
+- Regenerated the F-Droid catalog `icon.png` (512x512, both locales) so it
+  is pixel-faithful to the on-device adaptive launcher icon: same slate
+  background (`#5C6B7A`), off-white mark (`#FAF6F0`), and the foreground
+  group transform (`scale 0.5`, pivot `114,108`, translate `2,8`) baked in.
+- Added `design/icon/calendula_launcher.svg` — the composed full-bleed
+  icon (background + transformed mark) as the single source of truth for
+  store/F-Droid renders.
+
 ## [0.2.0] — 2026-06-08
 
 ### Added