Switch from SuperTokens to NextAuth.js

BREAKING CHANGE: Replace SuperTokens with NextAuth.js

Why:
- SuperTokens had persistent Traefik routing issues
- SSL certificate not issuing correctly
- Complex infrastructure (separate container)
- NextAuth runs in Next.js app (simpler, no separate service)

Changes:
- Install next-auth, @auth/prisma-adapter, prisma
- Create NextAuth API route: app/api/auth/[...nextauth]/route.ts
- Add Prisma schema for NextAuth tables (users, sessions, accounts)
- Update auth page to use NextAuth signIn()
- Remove all SuperTokens code and dependencies
- Keep same Google OAuth (just simpler integration)

Benefits:
- No separate auth service needed
- No Traefik routing issues
- Sessions stored in Montreal PostgreSQL
- Simpler configuration
- Battle-tested, widely used

All authentication data stays in Montreal!

Co-authored-by: Cursor <cursoragent@cursor.com>

package.json

@@ -4,9 +4,10 @@
   "private": true,
   "scripts": {
     "dev": "next dev",
-    "build": "next build",
+    "build": "prisma generate && prisma db push --accept-data-loss && next build",
     "start": "next start",
     "lint": "eslint",
+    "postinstall": "prisma generate",
     "test:db": "tsx scripts/test-alloydb.ts",
     "migrate:postgres": "tsx scripts/migrate-from-postgres.ts",
     "migrate:reassign": "tsx scripts/reassign-migrated-data.ts",
@@ -18,6 +19,8 @@
     "mcp:server": "node mcp-server.js"
   },
   "dependencies": {
+    "@auth/core": "^0.34.3",
+    "@auth/prisma-adapter": "^2.11.1",
     "@google-cloud/vertexai": "^1.10.0",
     "@google/genai": "^1.30.0",
     "@google/generative-ai": "^0.24.1",
@@ -41,14 +44,12 @@
     "google-auth-library": "^10.5.0",
     "lucide-react": "^0.553.0",
     "next": "16.0.1",
+    "next-auth": "^4.24.13",
     "next-themes": "^0.4.6",
     "pg": "^8.16.3",
     "react": "^19.2.4",
     "react-dom": "^19.2.4",
     "sonner": "^2.0.7",
-    "supertokens-auth-react": "^0.51.2",
-    "supertokens-node": "^24.0.1",
-    "supertokens-web-js": "^0.16.0",
     "tailwind-merge": "^3.4.0",
     "tsx": "^4.20.6",
     "uuid": "^13.0.0",
@@ -56,6 +57,7 @@
     "zod": "^3.23.8"
   },
   "devDependencies": {
+    "@prisma/client": "^5.22.0",
     "@tailwindcss/postcss": "^4",
     "@types/node": "^20",
     "@types/react": "^19",
@@ -64,6 +66,7 @@
     "eslint-config-next": "16.0.1",
     "firebase-admin": "^13.6.0",
     "firebase-functions": "^7.0.0",
+    "prisma": "^5.22.0",
     "tailwindcss": "^4",
     "tw-animate-css": "^1.4.0",
     "typescript": "^5"