- Add userId check to /api/notes/reorder (was completely unprotected)
- Scope syncNoteTags by userId to prevent cross-user tag pollution
- Verify attachmentId belongs to noteId in attachment operations (IDOR fix)
- Remove DEFAULT 0 from userId columns so missing userId fails loudly
- Update test helpers and test data to provide required userId
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
