desktop M10.4: Rust local SQLite store + Tauri commands

The on-device core that makes the desktop app work with no server and no login.

- rusqlite (bundled SQLite, so no system libsqlite dependency to vary across
  builds); uuid v4 ids; RFC3339/Date.toISOString-compatible timestamps.
- Schema mirroring the note model: notes, labels, note_labels (with via_tag),
  checklist_items, attachments, link_previews, note_revisions, saved_filters,
  plus per-row sync_revision/dirty + a sync_state row for the M10.7 engine.
  user_version-gated migrations.
- derive.rs: pure [[wiki-link]] + #tag scanners (mirror the frontend inline
  rules, no regex dep) with unit tests; #tags re-sync via_tag labels on save,
  [[links]] drive backlinks at query time (derived, never stored).
- store.rs: the full repository surface (facet/label/date/text list, create,
  PATCH-semantics update, pin/archive/color/kind, checklist items, labels CRUD
  + merge, reminders complete/snooze, reorder, trash/restore/delete, revisions
  + restore, titles/search/backlinks/link-search, saved filters).
- commands.rs: ~38 #[tauri::command]s over a Mutex<Connection> in managed state.
- lib.rs: opens the DB in the platform app-data dir on setup; synthetic offline
  config/user so the auth-gated router resolves with no login.

Attachment upload / URL unfurl / import are intentionally deferred (network/file
concerns); adapters/local.ts (M10.5) wires all of the above via invoke.

Task 1993.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FRgehjoz7Yv8LkUfADxACm

desktop/src-tauri/Cargo.toml

@@ -18,6 +18,12 @@ tauri-build = { version = "2", features = [] }
 tauri = { version = "2", features = [] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+# Local-first store (M10.4): bundled = compile SQLite in, so there's no system
+# libsqlite dependency to vary across the AppImage / native / Windows builds.
+rusqlite = { version = "0.32", features = ["bundled"] }
+uuid = { version = "1", features = ["v4"] }
+# RFC3339 timestamps for created_at/updated_at/remind_at (Date.parse-able on the JS side).
+chrono = { version = "0.4", default-features = false, features = ["clock"] }
 
 # Tauri's default release profile: smaller, faster shipped binaries.
 [profile.release]