Follow-up to #97, on the same release line. After the visibility fix a calendar can be absent from the pickers for three different reasons the app knows and never said; this closes that gap.
**Settings → Calendars names the state** (#76, #78): read-only calendars are marked `Read-only`; ones whose account isn't syncing events to this device are marked `Not synced`, sorted to the bottom of their account, dimmed, and left **without a switch** — visibility can't reveal events that aren't on the device, so the control did nothing.
**Both pickers end in a "Missing a calendar?" row** (#76) opening the calendar manager, where those labels then say which reason applies. The manager overlay moved to the end of the host's overlay stack so it covers every surface that can open it (Settings, both event forms, the import picker).
Review notes:
- **Supporting text, not chips.** A row can carry several states at once next to a live switch; M3 supporting text composes there, static badges don't (and a non-interactive chip reads as a broken button).
- **`sync_events = 0` counts as "not synced" for account-backed calendars only.** Nothing syncs a device-local calendar by definition, and another app's local calendar can hold real events at 0 — the unsoundness that made the first #75 migration guard wrong. Covered by a test.
- **Excluded calendars stay out of the pickers** rather than being listed unpickable — a handful of read-only subscriptions would crowd out the ones you can actually choose.
541 JVM tests green (6 new), lint clean, check_translations clean. **On-device review owed**; the three new string keys need the Weblate backfill.
Reviewed-on: #101
Jean-Luc Makiola
8e2109d073