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>

app/src/test/java/de/jeanlucmakiola/calendula/domain/EventFormTest.kt

@@ -112,21 +112,24 @@ class EventFormTest {
         reminders: List<Reminder> = emptyList(),
         availability: Availability = Availability.Busy,
         accessLevel: AccessLevel = AccessLevel.Default,
+        rowStart: Long = 0L,
+        rowEnd: Long = 0L,
+        attendees: List<Attendee> = emptyList(),
     ): EventDetail = EventDetail(
         instance = EventInstance(
             instanceId = 1L,
             eventId = 1L,
             calendarId = 7L,
             title = title,
-            start = Instant.fromEpochMilliseconds(0L),
-            end = Instant.fromEpochMilliseconds(0L),
+            start = Instant.fromEpochMilliseconds(rowStart),
+            end = Instant.fromEpochMilliseconds(rowEnd),
             isAllDay = isAllDay,
             color = 0,
             location = location,
         ),
         description = description,
         organizer = null,
-        attendees = emptyList(),
+        attendees = attendees,
         rrule = rrule,
         reminders = reminders,
         availability = availability,
@@ -177,6 +180,41 @@ class EventFormTest {
         assertThat(prefilled.rrule).isEqualTo("FREQ=WEEKLY")
     }
 
+    @Test
+    fun `snapshots of an unchanged event are equal`() {
+        val a = detail().toEditSnapshot(0L, 3_600_000L, berlin)
+        val b = detail().toEditSnapshot(0L, 3_600_000L, berlin)
+        assertThat(b).isEqualTo(a)
+    }
+
+    @Test
+    fun `an external field change makes snapshots differ`() {
+        val loaded = detail().toEditSnapshot(0L, 3_600_000L, berlin)
+        val fresh = detail(title = "Stand-up (moved)").toEditSnapshot(0L, 3_600_000L, berlin)
+        assertThat(fresh).isNotEqualTo(loaded)
+    }
+
+    @Test
+    fun `an external time move is caught by the row times the form cannot see`() {
+        // Both snapshots are taken for the same tapped occurrence, so the
+        // *forms* derive identical times — only rowStart/rowEnd betray the move.
+        val loaded = detail(rrule = "FREQ=WEEKLY", rowStart = 0L)
+            .toEditSnapshot(0L, 3_600_000L, berlin)
+        val fresh = detail(rrule = "FREQ=WEEKLY", rowStart = 86_400_000L)
+            .toEditSnapshot(0L, 3_600_000L, berlin)
+        assertThat(fresh.form).isEqualTo(loaded.form)
+        assertThat(fresh).isNotEqualTo(loaded)
+    }
+
+    @Test
+    fun `changes the form cannot write do not fake a conflict`() {
+        val loaded = detail().toEditSnapshot(0L, 3_600_000L, berlin)
+        val fresh = detail(
+            attendees = listOf(Attendee("Ada", "ada@example.org", AttendeeStatus.Accepted)),
+        ).toEditSnapshot(0L, 3_600_000L, berlin)
+        assertThat(fresh).isEqualTo(loaded)
+    }
+
     @Test
     fun `populatedFields reports exactly the sections holding values`() {
         val empty = form().copy(location = "", description = "")