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>

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

@@ -0,0 +1,6 @@
+import NextAuth from "next-auth";
+import { authOptions } from "@/lib/auth/authOptions";
+
+const handler = NextAuth(authOptions);
+
+export { handler as GET, handler as POST };

app/api/auth/[[...path]]/route.ts

@@ -1,60 +0,0 @@
-import { NextRequest, NextResponse } from "next/server";
-import SuperTokens from "supertokens-node";
-import { backendConfig } from "@/lib/supertokens/backendConfig";
-import { getAppDirRequestHandler } from "supertokens-node/nextjs";
-
-// Tell Next.js this is a dynamic route (don't evaluate at build time)
-export const dynamic = 'force-dynamic';
-export const runtime = 'nodejs';
-
-// Initialize SuperTokens lazily (only when first request comes in)
-let initialized = false;
-
-function ensureInitialized() {
-  if (!initialized && typeof window === 'undefined') {
-    SuperTokens.init(backendConfig());
-    initialized = true;
-  }
-}
-
-export async function GET(request: NextRequest) {
-  ensureInitialized();
-  const handleRequest = getAppDirRequestHandler(NextResponse);
-  const response = await handleRequest(request);
-  return response;
-}
-
-export async function POST(request: NextRequest) {
-  ensureInitialized();
-  const handleRequest = getAppDirRequestHandler(NextResponse);
-  const response = await handleRequest(request);
-  return response;
-}
-
-export async function DELETE(request: NextRequest) {
-  ensureInitialized();
-  const handleRequest = getAppDirRequestHandler(NextResponse);
-  const response = await handleRequest(request);
-  return response;
-}
-
-export async function PUT(request: NextRequest) {
-  ensureInitialized();
-  const handleRequest = getAppDirRequestHandler(NextResponse);
-  const response = await handleRequest(request);
-  return response;
-}
-
-export async function PATCH(request: NextRequest) {
-  ensureInitialized();
-  const handleRequest = getAppDirRequestHandler(NextResponse);
-  const response = await handleRequest(request);
-  return response;
-}
-
-export async function HEAD(request: NextRequest) {
-  ensureInitialized();
-  const handleRequest = getAppDirRequestHandler(NextResponse);
-  const response = await handleRequest(request);
-  return response;
-}