Move the accumulated [Unreleased] section under [2.12.0] — 2026-06-28 and
regenerate fastlane/.../changelogs/21200.txt from it (scripts/
sync_changelog_to_fastlane.sh), so the official F-Droid listing and the
Gitea release notes both cover the release's two changes: the past-event
display settings (agenda screen + widget, month/week dimming) and the
overlapping-event title wrapping. versionName is already 2.12.0/21200.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Bump versionName to 2.12.0 (versionCode 21200) and add the changelog.
Merging this into main triggers release.yaml, which builds, signs,
publishes and mints the v2.12.0 tag + Gitea release.
Closes #13
