remove jellyfin, mqtt, webhook services, fix tests, add schema migrations

- delete server/services/jellyfin.ts, webhook.ts, mqtt.ts and their tests
- strip jellyfin/mqtt imports and startup calls from index.tsx and settings.ts
- remove /jellyfin, /mqtt, /mqtt/status, /mqtt/test, /jellyfin/webhook-plugin endpoints from settings router
- clean ENV_MAP and isEnvConfigured of jellyfin/mqtt keys
- add db/index.ts migrations for series_key, duration_seconds, scan_status, scan_error, last_scanned_at (new columns absent on older dev DBs)
- move idx_media_items_series_key out of SCHEMA into migrate() so it runs after the column is added
- fix all test fixtures: drop jellyfin_id/series_jellyfin_id column refs, update MediaItem/MediaStream object literals to match current types

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/services/__tests__/ffmpeg.test.ts

@@ -8,7 +8,6 @@ function stream(o: Partial<MediaStream> & Pick<MediaStream, "id" | "type" | "str
 		codec: null,
 		profile: null,
 		language: null,
-		language_display: null,
 		title: null,
 		is_default: 0,
 		is_forced: 0,
@@ -36,28 +35,23 @@ function decision(o: Partial<StreamDecision> & Pick<StreamDecision, "stream_id"
 
 const ITEM: MediaItem = {
 	id: 1,
-	jellyfin_id: "x",
 	type: "Movie",
 	name: "Test",
-	original_title: null,
 	series_name: null,
-	series_jellyfin_id: null,
+	series_key: null,
 	season_number: null,
 	episode_number: null,
 	year: null,
 	file_path: "/movies/Test.mkv",
 	file_size: null,
 	container: "mkv",
-	runtime_ticks: null,
-	date_last_refreshed: null,
+	duration_seconds: null,
 	original_language: "eng",
-	orig_lang_source: "jellyfin",
+	orig_lang_source: "probe",
 	needs_review: 0,
 	imdb_id: null,
 	tmdb_id: null,
 	tvdb_id: null,
-	jellyfin_raw: null,
-	external_raw: null,
 	scan_status: "scanned",
 	scan_error: null,
 	last_scanned_at: null,