feat(edit): form redesign, optional fields, OptionCard dialogs, expressive motion

Post-v1.2.0 design iteration on the event form, reviewed slice by slice
on-device:

- Form rebuilt on the detail screen's card system: tonal EditCards with
  gutter icons (centred on the first row, top-aligned for multiline),
  borderless inline fields (placeholders at half opacity), calendar-coloured
  title accent, no dividers, bare top bar
- Optional sections (location, description, reminders, availability,
  visibility) with per-user defaults in Settings ("New event form" toggles);
  hidden ones unfold via a "More fields" picker dialog
- Reminders: stacked rows + full-width borderless add; two-step picker
  (one-tap presets, then custom amount + minutes/hours/days/weeks dropdown);
  written as METHOD_ALERT Reminders rows. Availability busy/free segmented
  toggle; visibility selector with per-level icons
- OptionCard (ui/common) is now the app-wide selection-dialog standard;
  calendar picker, visibility, more-fields, reminder presets and the
  recurring-delete chooser all use it — radio-row dialogs removed
- MaterialExpressiveTheme with MotionScheme.standard() (expressive bounce
  felt overdone); FAB stack + field reveals animate on theme springs;
  jump-to-today slides toward today's actual direction
- IME: adjustResize + imePadding so the keyboard never pans the form
- Tests: form-field prefs round-trips, availability/access provider
  mappings; DE+EN strings throughout

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

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

@@ -67,6 +67,20 @@
     <string name="event_edit_error_no_calendar">Kein beschreibbarer Kalender verfügbar</string>
     <string name="event_edit_save_failed">Termin konnte nicht gespeichert werden</string>
     <string name="event_edit_write_denied">Calendula braucht Schreibzugriff, um Termine zu erstellen</string>
+    <string name="event_edit_more_fields">Weitere Felder</string>
+    <string name="event_edit_add">Hinzufügen</string>
+    <string name="event_edit_add_reminder">Erinnerung hinzufügen</string>
+    <string name="event_edit_remove_reminder">Erinnerung entfernen</string>
+    <string name="event_edit_reminder_custom">Benutzerdefiniert</string>
+    <string name="reminder_unit_minutes">Minuten</string>
+    <string name="reminder_unit_hours">Stunden</string>
+    <string name="reminder_unit_days">Tage</string>
+    <string name="reminder_unit_weeks">Wochen</string>
+    <string name="event_edit_availability">Verfügbarkeit</string>
+    <string name="event_edit_visibility">Sichtbarkeit</string>
+    <string name="event_availability_busy">Beschäftigt</string>
+    <string name="event_access_default">Standard</string>
+    <string name="event_access_public">Öffentlich</string>
     <string name="event_detail_all_day">Ganztägig</string>
     <string name="event_detail_calendar">Kalender</string>
     <string name="event_detail_calendar_unknown">Unbekannter Kalender</string>
@@ -149,6 +163,8 @@
     <string name="settings_week_start_auto">Automatisch</string>
     <string name="settings_week_start_monday">Montag</string>
     <string name="settings_week_start_sunday">Sonntag</string>
+    <string name="settings_section_event_form">Termin-Formular</string>
+    <string name="settings_form_fields_hint">Standardmäßig angezeigte Felder — alles Weitere liegt hinter \"Weitere Felder\"</string>
     <string name="settings_section_language">Sprache</string>
     <string name="settings_language">App-Sprache</string>
     <string name="settings_language_auto">Systemstandard</string>