release: cut v2.5.0 — home-screen widgets, agenda, jump-to-date, quick actions

Bundles the unreleased Tier 2/3 work into one release:

- Home-screen widgets (Glance): an "Upcoming" agenda widget and a month-grid
  widget, both reusing the in-app grouping/layout (groupAgendaDays,
  layoutMonthWeeks) via a Hilt WidgetEntryPoint, honouring hidden-calendar
  filters and refreshing on PROVIDER_CHANGED / date rollover.
- App shortcut: launcher long-press "New event", routed through the shared
  WidgetNavRequest.Create channel into the create-event form.
- Agenda view and jump-to-date (already merged via #3/#4) are documented here
  as part of the shipped version.

Bumps versionCode 20500 / versionName 2.5.0, moves the CHANGELOG Unreleased
section under [2.5.0], updates ROADMAP/STATE, and adds EN+DE strings.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/build.gradle.kts

@@ -28,8 +28,8 @@ android {
         // the tag, with versionCode = MAJOR*10000 + MINOR*100 + PATCH
         // (e.g. v2.0.0 -> 20000). These committed values are the dev/local
         // default; keep them matching the latest released tag. See docs/RELEASING.md.
-        versionCode = 20400
-        versionName = "2.4.0"
+        versionCode = 20500
+        versionName = "2.5.0"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }
@@ -113,6 +113,9 @@ dependencies {
 
     implementation(libs.androidx.datastore.preferences)
 
+    implementation(libs.androidx.glance.appwidget)
+    implementation(libs.androidx.glance.material3)
+
     implementation(libs.kotlinx.datetime)
     implementation(libs.kotlinx.coroutines.core)