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/lib/server-url.ts

@@ -0,0 +1,10 @@
+const STORAGE_KEY = "aelis-server-url"
+const DEFAULT_URL = "https://3000--019cf276-6ed6-7529-a425-210182693908.eu-runner.flex.doptig.cloud"
+
+export function getServerUrl(): string {
+  return localStorage.getItem(STORAGE_KEY) ?? DEFAULT_URL
+}
+
+export function setServerUrl(url: string): void {
+  localStorage.setItem(STORAGE_KEY, url.replace(/\/+$/, ""))
+}