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/src/main/res/values-de/strings.xml

@@ -209,6 +209,21 @@
     <string name="agenda_empty_title">Nichts geplant</string>
     <string name="agenda_empty_subtitle">Anstehende Termine erscheinen hier.</string>
 
+    <!-- Startbildschirm-Widgets -->
+    <string name="widget_agenda_title">Anstehend</string>
+    <string name="widget_agenda_label">Calendula Agenda</string>
+    <string name="widget_month_label">Calendula Monat</string>
+    <string name="widget_refresh">Aktualisieren</string>
+    <string name="widget_new_event">Neuer Termin</string>
+    <string name="widget_needs_permission">Öffne Calendula, um Kalenderzugriff zu erlauben</string>
+    <string name="widget_prev_month">Vorheriger Monat</string>
+    <string name="widget_next_month">Nächster Monat</string>
+    <string name="widget_today">Heute</string>
+
+    <!-- Verknüpfungen (Long-Press auf das App-Symbol) -->
+    <string name="shortcut_new_event_short">Neuer Termin</string>
+    <string name="shortcut_new_event_long">Neuen Termin erstellen</string>
+
     <!-- Kalender-Filter (M3) -->
     <string name="filter_title">Kalender</string>