* feat: bundled JSON release notes for 4.0, polished changelog sheet, remove IAP
- Move release-note content from ARB to assets/release_notes/<locale>.json
with locale-fallback repository and schema-checked validator
- Polish the release notes sheet (staggered reveal, version badge,
feature glyph bullets, action cards) and add the 4.0 note in 13 locales
- Prune pre-4.0 notes
- Remove in_app_purchase and the tip jar entirely; keep the Buy Me a
Coffee donation link on all platforms
* Refresh release notes sheet and localized copy
* Add release notes banner and native review support
* Redesign release announcement sheet
* Target release announcement to 4.0.1
* Address release announcement review feedback
* Tighten release note locale handling
