fix: wrap login page in Suspense (useSearchParams prerender crash)

- /login page used useSearchParams() without Suspense boundary
- Next.js 16 requires Suspense for useSearchParams during static prerender
- Extracted LoginForm component, wrapped in <Suspense>
- Removed --webpack flag (default Turbopack build now works)
- Build passes cleanly: ✓ Compiled successfully

package.json

@@ -9,7 +9,7 @@
   "scripts": {
     "dev": "next dev -p 3000",
     "dev:log": "next dev -p 3000 2>&1 | tee dev.log",
-    "build": "prisma generate && next build --webpack && cp -r .next/static .next/standalone/.next/ && cp -r public .next/standalone/",
+    "build": "prisma generate && next build && cp -r .next/static .next/standalone/.next/ && cp -r public .next/standalone/",
     "start": "NODE_ENV=production bun .next/standalone/server.js 2>&1 | tee server.log",
     "lint": "eslint .",
     "db:push": "prisma db push --accept-data-loss",