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

src/app/login/page.tsx

@@ -1,13 +1,13 @@
 'use client'
 
-import { useState } from 'react'
+import { Suspense, useState } from 'react'
 import { useRouter, useSearchParams } from 'next/navigation'
 import { Button } from '@/components/ui/button'
 import { Input } from '@/components/ui/input'
 import { Label } from '@/components/ui/label'
 import { Loader2, Lock } from 'lucide-react'
 
-export default function LoginPage() {
+function LoginForm() {
   const router = useRouter()
   const searchParams = useSearchParams()
   const redirect = searchParams.get('redirect') || '/'
@@ -40,6 +40,32 @@ export default function LoginPage() {
     }
   }
 
+  return (
+    <form onSubmit={handleSubmit} className="space-y-4">
+      <div className="space-y-2">
+        <Label htmlFor="password">Passwort</Label>
+        <Input
+          id="password"
+          type="password"
+          value={password}
+          onChange={(e) => setPassword(e.target.value)}
+          placeholder="Admin-Passwort eingeben"
+          autoFocus
+          autoComplete="current-password"
+        />
+      </div>
+      {error && (
+        <p className="text-sm text-red-600 dark:text-red-400">{error}</p>
+      )}
+      <Button type="submit" className="w-full gap-2" disabled={loading || !password}>
+        {loading && <Loader2 className="size-4 animate-spin" />}
+        Anmelden
+      </Button>
+    </form>
+  )
+}
+
+export default function LoginPage() {
   return (
     <div className="flex min-h-screen items-center justify-center bg-background p-4">
       <div className="w-full max-w-sm space-y-6">
@@ -53,27 +79,9 @@ export default function LoginPage() {
           </p>
         </div>
 
-        <form onSubmit={handleSubmit} className="space-y-4">
-          <div className="space-y-2">
-            <Label htmlFor="password">Passwort</Label>
-            <Input
-              id="password"
-              type="password"
-              value={password}
-              onChange={(e) => setPassword(e.target.value)}
-              placeholder="Admin-Passwort eingeben"
-              autoFocus
-              autoComplete="current-password"
-            />
-          </div>
-          {error && (
-            <p className="text-sm text-red-600 dark:text-red-400">{error}</p>
-          )}
-          <Button type="submit" className="w-full gap-2" disabled={loading || !password}>
-            {loading && <Loader2 className="size-4 animate-spin" />}
-            Anmelden
-          </Button>
-        </form>
+        <Suspense fallback={<div className="text-center text-sm text-muted-foreground">Laden…</div>}>
+          <LoginForm />
+        </Suspense>
 
         <p className="text-center text-xs text-muted-foreground">
           Geschützter Bereich — nur für autorisierte Benutzer.