feat(event-form): auto-focus the title on a new event, optionally (#10)

Opening the new-event form now puts the cursor in the title field and raises the
keyboard, so the user can type the name straight away instead of tapping the
field first (issue #10). On by default — most events get a title — with a new
"Focus title on new event" switch in Settings → New event form to turn it off.

Only the create form auto-focuses: editing an existing event and opening a
prefilled/imported form never grab focus (guarded by !isEditing && title blank).

- SettingsPrefs: autofocusEventTitle (booleanPreferencesKey), default true.
- Plumbed through SettingsViewModel/UiState (settings switch) and
  EventEditViewModel/UiState (read by the form).
- EventEditScreen: a FocusRequester on the title InlineField, requested once per
  open from a LaunchedEffect when the guard holds.
- Strings (en + de), unit test for the new pref default/round-trip.

Bumps to 2.11.2.

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

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

@@ -303,6 +303,8 @@
     </plurals>
     <string name="settings_section_event_form">New event form</string>
     <string name="settings_form_fields_hint">Fields shown by default — everything else sits behind \"More fields\"</string>
+    <string name="settings_autofocus_title">Focus title on new event</string>
+    <string name="settings_autofocus_title_hint">When you start a new event, place the cursor in the title field and open the keyboard right away.</string>
     <string name="settings_color_unsupported">Allow colors on unsupported calendars</string>
     <string name="settings_color_unsupported_hint">Some calendars (e.g. certain CalDAV) publish no color set; a custom event color may be dropped or overwritten on their next sync. That\'s a limitation of those calendars, not something Calendula can fix.</string>
     <string name="settings_section_notifications">Notifications</string>