feat: add admin dashboard app (#91)

* feat: add admin dashboard app

- React + Vite + TanStack Router + TanStack Query
- Auth with better-auth (login, session, admin guard)
- Source config management (WeatherKit credentials, user config)
- Feed query panel
- Location push card
- General settings with health check
- CORS middleware for cross-origin auth
- Disable CSRF check in dev mode
- Sonner toasts for mutation feedback

Co-authored-by: Ona <no-reply@ona.com>

* fix: use useQuery instead of getQueryData

Co-authored-by: Ona <no-reply@ona.com>

* refactor: remove backend changes from dashboard PR

Backend CORS/CSRF changes moved to #92.
Source registry removed (sources hardcoded in frontend).

Co-authored-by: Ona <no-reply@ona.com>

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Co-authored-by: Ona <no-reply@ona.com>

apps/admin-dashboard/.prettierignore

@@ -0,0 +1,7 @@
+node_modules/
+coverage/
+.pnpm-store/
+pnpm-lock.yaml
+package-lock.json
+pnpm-lock.yaml
+yarn.lock