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/sources.$sourceId.tsx

@@ -0,0 +1,34 @@
+import { createRoute } from "@tanstack/react-router"
+import { useQuery, useQueryClient } from "@tanstack/react-query"
+
+import { fetchSources } from "@/lib/api"
+import { SourceConfigPanel } from "@/components/source-config-panel"
+import { Route as dashboardRoute } from "../_dashboard"
+
+export const Route = createRoute({
+  getParentRoute: () => dashboardRoute,
+  path: "/sources/$sourceId",
+  component: SourceRoute,
+})
+
+function SourceRoute() {
+  const { sourceId } = Route.useParams()
+  const queryClient = useQueryClient()
+  const { data: sources = [] } = useQuery({
+    queryKey: ["sources"],
+    queryFn: fetchSources,
+  })
+  const source = sources.find((s) => s.id === sourceId)
+
+  if (!source) {
+    return <p className="text-sm text-muted-foreground">Source not found.</p>
+  }
+
+  return (
+    <SourceConfigPanel
+      key={source.id}
+      source={source}
+      onUpdate={() => queryClient.invalidateQueries({ queryKey: ["configs"] })}
+    />
+  )
+}