feat(concerts): show artwork-themed event details in app

docs/artist_concerts.md

@@ -13,6 +13,7 @@ Older extensions may omit it; no concert button is shown for an empty list.
     "venue": "Example Hall",
     "start_at": "2026-10-07T01:00:00Z",
     "time_zone": "America/New_York",
+    "detail_id": "event-123",
     "url": "https://example.com/events/123"
   }]
 }
@@ -26,7 +27,8 @@ Older extensions may omit it; no concert button is shown for an empty list.
   preserves the wall-clock fields supplied in `start_at`.
 - `id`, `venue`, and `url` are optional. The app deduplicates by event ID (or
   date/location/venue), orders events by date, and accepts at most 500 entries.
-- Only HTTP(S) event links can be opened, and only after tapping an event.
+- Tapping an event opens its internal detail page. Only explicit ticket and map
+  actions open external HTTP(S) links; the event URL is used for sharing.
 - Providers should return upcoming events only. Failure to fetch this optional
   information must not fail the artist's albums or top tracks.
 
@@ -34,3 +36,41 @@ The badge opens a native schedule with artist identity, venue-local date tiles,
 and event details. Labels are provider-neutral in both application themes.
 Concert metadata is supplied with the artist response, so the schedule opens
 immediately without a second loading state or network request.
+
+The schedule follows the application's light/dark theme. The detail page uses
+the artist portrait's palette and light text in either theme, including its
+loading placeholders. Any metadata extension can implement `getConcert(id)`
+and supply `detail_id` on its events. The app requests it only when opening an
+event through `getProviderMetadata(provider, "concert", detail_id)`, receiving
+the generic `concert` envelope. Older providers without `detail_id` still open
+a detail page with the schedule's date and venue.
+
+```json
+{
+  "id": "event-123",
+  "artist_name": "Example Artist",
+  "title": "Example Tour",
+  "cover_url": "https://example.com/artist.jpg",
+  "start_at": "2026-10-07T01:00:00Z",
+  "end_at": "2026-10-07T04:00:00Z",
+  "time_zone": "America/New_York",
+  "venue": "Example Hall",
+  "address": "123 Example Street",
+  "ticket_url": "https://example.com/tickets/123",
+  "map_url": "https://example.com/maps/123",
+  "url": "https://example.com/events/123",
+  "attribution": "Powered by Example Events",
+  "set_list": {
+    "id": "playlist-123",
+    "name": "Example Tour Set List",
+    "cover_url": "https://example.com/set-list.jpg"
+  }
+}
+```
+
+All detail fields are optional. Omit unavailable actions instead of fabricating
+links. Set lists open the existing internal playlist screen using the same
+metadata provider. Calendar actions present a system editor for the user to
+review and save; no event is added automatically. iOS 17+ needs no calendar
+read permission; iOS 16 requests legacy permission. Android uses an insert
+intent. Failed detail requests leave the date and venue visible with Retry.