mobile2: Casdoor OIDC auth deployment

- New branch for mobile2.falah-os.com with Casdoor OIDC
- Auth page with 'Sign in with Casdoor' button
- OIDC callback: exchanges code via server-side API route
- env vars configured on Netlify
- DNS auto-configured via Netlify (falah-os.com zone)

next.config.ts

@@ -1,4 +1,5 @@
 import type { NextConfig } from "next";
+import path from "path";
 
 const nextConfig: NextConfig = {
   basePath: "/mobile",
@@ -8,6 +9,9 @@ const nextConfig: NextConfig = {
   experimental: {
     optimizePackageImports: ["lucide-react"],
   },
+  turbopack: {
+    root: path.resolve(import.meta.dirname || __dirname),
+  },
 };
 
 export default nextConfig;