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>

app/src/main/AndroidManifest.xml

@@ -23,6 +23,17 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+
+        <!-- Persists the per-app language (M4) on API < 33, where the platform
+             per-app-languages API is unavailable. On 33+ this is a no-op. -->
+        <service
+            android:name="androidx.appcompat.app.AppLocalesMetadataHolderService"
+            android:enabled="false"
+            android:exported="false">
+            <meta-data
+                android:name="autoStoreLocales"
+                android:value="true" />
+        </service>
     </application>
 
 </manifest>