feat(edit): conflict dialog on save + store metadata refresh (v2.0)

No locking (plan 03, decision 5): openForEdit keeps an EditSnapshot — the
prefilled form plus the raw Events-row times, which the form itself can't
see (it derives its times from the tapped occurrence, so an externally
moved event would otherwise stay invisible). Right before writing,
performSave re-reads the event and compares snapshots: a mismatch parks
the save in SaveUiState.AwaitingConflict carrying the already-chosen
recurring scope, and the dialog offers overwrite / discard / cancel
(OptionCard style). Overwrite still writes only dirty fields, so external
changes to untouched fields survive either way. A deleted event lands in
SaveUiState.Gone — an informational dialog that closes form and detail.
Fields the form can't write (attendees, status, self response, reminder
methods) are excluded from the comparison so sync noise can't fake a
conflict. The load-time zone is pinned in the EditTarget so a device
timezone change mid-edit can't either.

Store metadata: F-Droid descriptions (DE+EN) and the README stop claiming
read-only and now describe write support and reminder delivery. New
fastlane phoneScreenshots (6 per locale: week/month/day/detail/form/
reminder onboarding), captured on-device against demo-only calendars.

Tests: EditSnapshot equality (unchanged event, field change, row-time move
the form can't see, non-writable changes stay quiet).

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

README.md

@@ -8,10 +8,14 @@ word "calendar". Calendula reads from Android's built-in `CalendarContract`,
 so any calendar source synced to your device (CalDAV via DAVx5, Google,
 local, WebCal subscriptions, ...) is shown.
 
-## Features (V1)
+## Features
 
 - Month, Week, and Day views
-- Read-only event details (write support comes in V2)
+- Full event details — attendees, reminders, recurrence, availability, and more
+- Create, edit, and delete events — recurring events with scoped writes
+  (only this event / this and all following / whole series) and a simple
+  recurrence picker
+- Reminder notifications, delivered by Calendula itself (tap opens the event)
 - Multi-calendar visibility toggle
 - Material You Dynamic Color (Android 12+)
 - Light/Dark theme follows system