feat(filter,settings): calendar filter in drawer + settings (v0.5.0)

M3 — calendar filter: the navigation drawer now hosts the calendar list
inline (grouped by account, colour swatch + checkbox per calendar). Hidden
calendars are persisted app-side and filtered centrally in the repository,
so month/week/day re-filter live the moment a checkbox flips. Drawer trimmed
to Today, the calendar filter, and Settings, with leading icons and a clear
title/section type scale; the stubbed jump-to-date entry (M2) was removed.

M4 — settings: full-screen destination with appearance (theme System/Light/
Dark, Material You dynamic colour auto-disabled < API 31, week start Auto/Mon/
Sun), language (per-app locales via AppCompat, persisted to API 29), and an
about section (version, licence, source link). Theme is driven by one
activity-scoped settings source so changes apply app-wide at once. Week start
now drives the month grid and week view; Auto follows the locale.

Also:
- default view switched from month to week
- Settings screen handles system back (was closing the app)
- fix pre-existing NonObservableLocale/LocalContextConfigurationRead lint
  errors in EventDetailScreen so CI lint is green again
- versionName/versionCode bumped to 0.5.0 / 5

Tests: repository hidden-filter (incl. live re-emit), SettingsPrefs round-trip
+ week-start resolution, filter grouping. lint + unit tests + assembleDebug green.

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

gradle/libs.versions.toml

@@ -4,6 +4,7 @@ kotlin = "2.3.21"
 ksp = "2.3.9"
 hilt = "2.59.2"
 coreKtx = "1.19.0"
+appcompat = "1.7.1"
 lifecycleRuntime = "2.10.0"
 activityCompose = "1.13.0"
 composeBom = "2026.05.01"
@@ -27,6 +28,7 @@ androidxTestRules = "1.7.0"
 [libraries]
 # AndroidX core
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
+androidx-appcompat = { group = "androidx.appcompat", name = "appcompat", version.ref = "appcompat" }
 androidx-lifecycle-runtime-ktx = { group = "androidx.lifecycle", name = "lifecycle-runtime-ktx", version.ref = "lifecycleRuntime" }
 androidx-activity-compose = { group = "androidx.activity", name = "activity-compose", version.ref = "activityCompose" }