refactor(annotations): AnnotationService is a required constructor dependency

H1's doctrine applied to the annotation service, which had been left on
setters: NewMediaHandler/NewKoboHandler/NewKOReaderHandler/
NewSyncQueueProcessor(WithConfig) now take it as a parameter; the four
SetAnnotationService setters are deleted; wiring updated (main.go,
router/sync.go, test harness).

With the service unskippable, the 18 nil-guards and their plain-query
fallbacks die:
- media.go: the create fallbacks for notes/highlights/bookmarks (the
  bookmark one was the H3 census's Bug #1 — it dropped
  percentage/chapter_reference the sync path carries), the highlight
  PUT fallback, and the three delete-path plain deletes (tombstone is
  now the only delete semantics).
- kobo.go: both markup-ingest annotation loops (the bookmark fallback
  wrote the text into media_notes — a category error the fallback
  never should have had).
- koreader.go: all three push-stack guards.
- queue.go: the three "annotation service not available" errors in
  syncNote/syncHighlight/syncBookmark.

Behavior note: the deleted highlight create/PUT fallbacks were the only
paths passing note_id to the plain query — the sync service has no
NoteID field, so the web's highlight→note link was already being
dropped on the live path; this commit makes that pre-existing
limitation explicit rather than papering it over (surfacing note_id on
SaveHighlightRequest is left for a behavior commit that needs it).

Pins (now 20 incl. the 3 annotation CRUD suites) + H1 tests + both
unit suites green.

internal/router/sync.go

@@ -37,8 +37,7 @@ func registerSyncRoutes(cfg *Config) {
 	// Kobo sync routes (device authentication required)
 	// Kobo devices use URL path: /api/sync/kobo/{token}/markup
 	// API clients can use Authorization header: Authorization: Bearer {token}
-	koboHandler := handlers.NewKoboHandler(cfg.Queries, cfg.ConnManager, cfg.ProgressService)
-	koboHandler.SetAnnotationService(cfg.AnnotationService)
+	koboHandler := handlers.NewKoboHandler(cfg.Queries, cfg.ConnManager, cfg.ProgressService, cfg.AnnotationService)
 	koboHandler.SetLibraryService(cfg.LibraryService)
 	koboSync := e.Group("/api/sync/kobo/:token")
 	koboSync.POST("/markup", cfg.DeviceAuthMiddleware.Authenticate(koboHandler.Markup))