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>

---------

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

apps/admin-dashboard/src/routes/_dashboard/feed.tsx

@@ -0,0 +1,10 @@
+import { createRoute } from "@tanstack/react-router"
+
+import { FeedPanel } from "@/components/feed-panel"
+import { Route as dashboardRoute } from "../_dashboard"
+
+export const Route = createRoute({
+  getParentRoute: () => dashboardRoute,
+  path: "/feed",
+  component: FeedPanel,
+})