Sample Curator v0.1.4

feat(updater): in-app banner + Settings → Updates section (v0.1.4)

Replaces the native modal `ask()` dialog with an in-app surface:

- New `UpdateBanner` mounted just below HeaderBar (alongside
  OllamaBanner). When `status === 'available'` it shows the new
  version with `Install & Restart` and `Later`. `Later` dismisses for
  the session; the next launch's startup check resurfaces it.
- New `Settings → Updates` section: current version, last-checked
  (relative time, persisted in localStorage), `Check for Updates`
  button, install button when an update is available, and a status
  line that reflects every state of the check (idle/checking/up-to-
  date/available/installing/error).
- State centralized in `useUpdaterStore` (Zustand) so the banner and
  Settings see the same check/install machine. Errors now surface in
  Settings (no longer silent — useful for debugging the endpoint
  config).
- Startup hook (`useUpdater`) is now a thin wrapper that triggers the
  store's `check()` once on mount.

Tested: TS + Vite clean; cargo check clean; auto-update path
mechanically identical to v0.1.2/0.1.3 (same plugin calls).