feat(detail): full event read — surface every readable field (v0.6.0)

Round out the read-only model so the detail view shows everything
CalendarContract actually stores, ahead of write support.

Data layer:
- New domain types: Reminder, EventStatus, Availability, AccessLevel,
  AttendeeRelationship, AttendeeType; EventDetail gains reminders, status,
  availability, accessLevel, eventTimezone, selfStatus and Attendee gains
  relationship + type (all defaulted so existing callers compile)
- EventDetailProjection reads STATUS / AVAILABILITY / ACCESS_LEVEL /
  EVENT_TIMEZONE / SELF_ATTENDEE_STATUS; AttendeeProjection reads
  RELATIONSHIP + TYPE; new ReminderProjection queries CalendarContract.Reminders
- Mappers translate each provider integer code, guarding STATUS's null-vs-0
  ambiguity (0 == TENTATIVE) so an absent status reads as Confirmed
- Mapper unit tests cover every new column's codes

Detail UI:
- Status / availability / access chips under the title; cancelled also strikes
  the title through
- Reminders card with humanised lead times (plurals, DE + EN)
- Foreign-timezone card, shown only for timed events in a non-device zone
- Attendee role badges + the user's own "Your response: …" line
- http(s) URLs in the description are now tappable

URL field cut: CalendarContract exposes no Events.URL column (only the
CUSTOM_APP_URI app deep-link), so URLs are surfaced by linkifying the
description instead. Recorded in ROADMAP/CHANGELOG.

Version bumped to 0.6.0 / 6.

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

app/build.gradle.kts

@@ -23,8 +23,8 @@ android {
         applicationId = "de.jeanlucmakiola.calendula"
         minSdk = 29
         targetSdk = 36
-        versionCode = 5
-        versionName = "0.5.0"
+        versionCode = 6
+        versionName = "0.6.0"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }