Wire AnnotationService into SyncQueueProcessor and implement the three
previously-stubbed execute methods:
- syncHighlight: unmarshals syncData JSON into SaveHighlightRequest,
applies CRE→CFI conversion via AnnotationService
- syncNote: unmarshals into SaveNoteRequest
- syncBookmark: unmarshals into SaveBookmarkRequest
- Add SyncTypeBookmark to executeSync switch (was hitting default error)
Add enqueue methods for future offline/batch use:
- EnqueueHighlight / EnqueueNote / EnqueueBookmark
- Shared enqueueAnnotation helper creates queue items with
PriorityCriticalNote and 3 max attempts
- Update types (HighlightUpdate, NoteUpdate, BookmarkUpdate) mirror the
existing ProgressUpdate pattern
Existing handler behavior is unchanged — annotations still sync
synchronously via AnnotationService. The queue path is available for
retry-on-failure and offline batch processing scenarios.