[Web/PWA] Add annotations notepad and reading digest review surfaces

[AlphaMao1]

Parent

#11

What to build

Add the note-review surfaces that make highlights useful after they are created: a per-book annotations/notepad panel, annotation detail actions, jump back to source, and a digest/review view suitable for later Markdown export.

Acceptance criteria

• A per-book notepad/annotations panel lists highlights and notes for the current book.
• Users can open an annotation, see selected text, note text, chapter/location, and creation/update time.
• Users can jump from a notepad item back to the original reading location.
• Users can edit or delete notes/highlights according to the record-level sync semantics from [Web/PWA] Add selection floating menu for highlight, note, and Ask AI #16.
• A digest/review view groups useful highlights and notes by book/chapter or another clear structure.
• The digest/review data path is reusable by Markdown export in [Web/PWA] Add Markdown export and deletion semantics #20.
• Empty, loading, sync-failed, and offline-local-only states are visible.
• Desktop side panel and Android/narrow presentation follow the approved visual system.

Blocked by

• [Web/PWA] Add selection floating menu for highlight, note, and Ask AI #16
• [Web/PWA][UI] Apply selected visual system to app shell and core screens #23