v0.5.6

Fixes

• Empty (zero-byte) notes were dropped from the search index instead of being indexed, so a title-only note with no body never appeared in list_notes or search, and a fresh CouchDB vault of mostly empty notes cold-started with only the non-empty ones indexed. The index now distinguishes deleted notes from empty-but-present ones (#5, #6).
• Bump transitive deps (form-data, hono, undici) to clear high-severity npm audit advisories (CRLF injection, CORS wildcard reflection).