Frontend wrote `trashed` (lowercase) but Rust parser expected `Trashed`
(title-case via serde rename). On restart, the lowercase key didn't match,
defaulted to false, and trashed notes reappeared.
- Frontend: use title-case keys (Trashed, Trashed at) matching vault convention
- Rust: add serde aliases for lowercase keys (backward compat with already-written files)
- Add regression tests for both title-case and lowercase parsing
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>