- errorDialog + hints now use createStore (drop their bespoke listener arrays).
- theme/sidebarLayout/notifications/App filters/Playlists plSort use readMerged/
readJSON/writeJSON instead of inline try/JSON.parse/catch.
- Stats, SettingsPanel and App's channel filter/view tabs use usePersistedState
(the 3 sites that reinvented usePersistedTab inline).
- Every siftlode.* key now sourced from the LS registry (no scattered literals).
- Duplicate-tag create/rename hit the uq_tags_user_name constraint and 500'd; now caught and
returned as a clear 409 ('You already have a tag named …').
- New global error dialog (errorDialog store + ErrorDialog modal) for definitive server refusals;
the api layer wiring + mount land with the rest of the round.
- Modal now keeps a stack so ESC dismisses only the top modal — an error over the tag editor
closes the error and leaves the editor open.
