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/sync/queue.go

@@ -76,27 +76,24 @@ type SyncQueueItem struct {
 // NewSyncQueueProcessor requires the shared ProgressService — queue
 // progress entries flush through SaveProgress (the LWW-seeded canonical
 // writer); a nil service has nowhere to fall back to and must not be wired.
-func NewSyncQueueProcessor(db *database.Queries, progressSvc *ProgressService) *SyncQueueProcessor {
-	return NewSyncQueueProcessorWithConfig(db, progressSvc, 5*time.Second, 50)
+func NewSyncQueueProcessor(db *database.Queries, progressSvc *ProgressService, annotationSvc *AnnotationService) *SyncQueueProcessor {
+	return NewSyncQueueProcessorWithConfig(db, progressSvc, annotationSvc, 5*time.Second, 50)
 }
 
 // NewSyncQueueProcessorWithConfig constructs a processor with the given flush
 // interval and batch size. Used at startup to source values from the settings
 // registry.
-func NewSyncQueueProcessorWithConfig(db *database.Queries, progressSvc *ProgressService, interval time.Duration, batchSize int) *SyncQueueProcessor {
+func NewSyncQueueProcessorWithConfig(db *database.Queries, progressSvc *ProgressService, annotationSvc *AnnotationService, interval time.Duration, batchSize int) *SyncQueueProcessor {
 	return &SyncQueueProcessor{
-		db:           db,
-		progressSvc:  progressSvc,
-		progressChan: make(chan *ProgressUpdate, 100),
-		interval:     interval,
-		batchSize:    batchSize,
+		db:            db,
+		progressSvc:   progressSvc,
+		annotationSvc: annotationSvc,
+		progressChan:  make(chan *ProgressUpdate, 100),
+		interval:      interval,
+		batchSize:     batchSize,
 	}
 }
 
-func (p *SyncQueueProcessor) SetAnnotationService(svc *AnnotationService) {
-	p.annotationSvc = svc
-}
-
 func (p *SyncQueueProcessor) Start(ctx context.Context) {
 	log.Printf("Starting sync queue processor (interval: %v, batch: %d)", p.interval, p.batchSize)
 
@@ -461,10 +458,6 @@ func (p *SyncQueueProcessor) syncProgress(ctx context.Context, userID pgtype.UUI
 }
 
 func (p *SyncQueueProcessor) syncNote(ctx context.Context, userID pgtype.UUID, mediaItemID pgtype.UUID, syncData map[string]interface{}) error {
-	if p.annotationSvc == nil {
-		return fmt.Errorf("annotation service not available")
-	}
-
 	req := SaveNoteRequest{
 		MediaItemID: mediaItemID,
 		UserID:      userID,
@@ -497,10 +490,6 @@ func (p *SyncQueueProcessor) syncNote(ctx context.Context, userID pgtype.UUID, m
 }
 
 func (p *SyncQueueProcessor) syncHighlight(ctx context.Context, userID pgtype.UUID, mediaItemID pgtype.UUID, syncData map[string]interface{}) error {
-	if p.annotationSvc == nil {
-		return fmt.Errorf("annotation service not available")
-	}
-
 	req := SaveHighlightRequest{
 		MediaItemID: mediaItemID,
 		UserID:      userID,
@@ -548,10 +537,6 @@ func (p *SyncQueueProcessor) syncHighlight(ctx context.Context, userID pgtype.UU
 }
 
 func (p *SyncQueueProcessor) syncBookmark(ctx context.Context, userID pgtype.UUID, mediaItemID pgtype.UUID, syncData map[string]interface{}) error {
-	if p.annotationSvc == nil {
-		return fmt.Errorf("annotation service not available")
-	}
-
 	req := SaveBookmarkRequest{
 		MediaItemID: mediaItemID,
 		UserID:      userID,