Bump versionName to 2.11.0 (versionCode 21100) and add the 2.11.0
changelog: any-day week start (#3), 12/24-hour time format (#6),
optional timeline hour lines (#5), and agenda range limits (#4).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
