Add Next.js client app with Prisma and auth

Introduce a new 'client' Next.js app scaffold: configuration files (next.config.ts, eslint.config.mjs, postcss, tsconfig), Prisma config and schema, app routes including NextAuth API and server actions, session/provider utilities, proxy, public assets, README and .gitignore. Also add IDE project files under .idea and a root README to initialize the repository structure for development.

client/src/app/api/auth/[...nextauth]/route.ts

@@ -0,0 +1,46 @@
+//setup google auth
+//only allow google login and store the user in the database if they login for the first time
+
+import NextAuth, { type NextAuthOptions } from "next-auth";
+import GoogleProvider from "next-auth/providers/google";
+import { createUserOnFirstGoogleLogin } from "./serverActions";
+
+const googleClientId = process.env.GOOGLE_CLIENT_ID;
+const googleClientSecret = process.env.GOOGLE_CLIENT_SECRET;
+
+if (!googleClientId || !googleClientSecret) {
+	throw new Error(
+		"Missing Google OAuth env vars. Set GOOGLE_CLIENT_ID and GOOGLE_CLIENT_SECRET.",
+	);
+}
+
+export const authOptions: NextAuthOptions = {
+	providers: [
+		GoogleProvider({
+			clientId: googleClientId,
+			clientSecret: googleClientSecret,
+		}),
+	],
+	callbacks: {
+		async signIn({ user, account }) {
+			if (account?.provider !== "google") {
+				return false;
+			}
+
+			if (!user.email) {
+				return false;
+			}
+
+			await createUserOnFirstGoogleLogin({
+				email: user.email,
+				name: user.name,
+			});
+
+			return true;
+		},
+	},
+};
+
+const handler = NextAuth(authOptions);
+
+export { handler as GET, handler as POST };