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/README.md

@@ -0,0 +1,21 @@
+# React + TypeScript + Vite + shadcn/ui
+
+This is a template for a new Vite project with React, TypeScript, and shadcn/ui.
+
+## Adding components
+
+To add components to your app, run the following command:
+
+```bash
+npx shadcn@latest add button
+```
+
+This will place the ui components in the `src/components` directory.
+
+## Using components
+
+To use the components in your app, import them as follows:
+
+```tsx
+import { Button } from "@/components/ui/button"
+```