feat: initial project setup for Meme Studio

Next.js 14 App Router application for managing homophone pun game levels:

- Better Auth with Prisma adapter for authentication
- MySQL database with Prisma ORM
- Level CRUD operations with drag-and-drop reordering
- Tencent COS integration for image uploads
- shadcn/ui components with Tailwind CSS
- TanStack Query for server state management

app/(auth)/layout.tsx

@@ -0,0 +1,7 @@
+export default function AuthLayout({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  return <>{children}</>
+}

app/(auth)/login/page.tsx

@@ -0,0 +1,122 @@
+'use client'
+
+import { Suspense, useState } from 'react'
+import { useRouter, useSearchParams } from 'next/navigation'
+import { signIn } from '@/lib/auth-client'
+import { Button } from '@/components/ui/button'
+import { Input } from '@/components/ui/input'
+import { Label } from '@/components/ui/label'
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card'
+import { Spinner } from '@/components/ui/spinner'
+
+function LoginForm() {
+  const router = useRouter()
+  const searchParams = useSearchParams()
+  const callbackUrl = searchParams.get('callbackUrl') || '/levels'
+
+  const [email, setEmail] = useState('')
+  const [password, setPassword] = useState('')
+  const [error, setError] = useState('')
+  const [isLoading, setIsLoading] = useState(false)
+
+  const handleSubmit = async (e: React.FormEvent) => {
+    e.preventDefault()
+    setError('')
+    setIsLoading(true)
+
+    try {
+      const result = await signIn.email({
+        email,
+        password,
+      })
+
+      if (result.error) {
+        setError(result.error.message || '登录失败，请检查邮箱和密码')
+        setIsLoading(false)
+        return
+      }
+
+      router.push(callbackUrl)
+      router.refresh()
+    } catch {
+      setError('登录失败，请稍后重试')
+      setIsLoading(false)
+    }
+  }
+
+  return (
+    <Card className="w-full max-w-md">
+      <CardHeader className="text-center">
+        <CardTitle className="text-2xl">Meme Studio</CardTitle>
+        <CardDescription>谐音梗小游戏运营平台</CardDescription>
+      </CardHeader>
+      <CardContent>
+        <form onSubmit={handleSubmit} className="space-y-4">
+          {error && (
+            <div className="p-3 text-sm text-red-600 bg-red-50 border border-red-200 rounded-md">
+              {error}
+            </div>
+          )}
+          <div className="space-y-2">
+            <Label htmlFor="email">邮箱</Label>
+            <Input
+              id="email"
+              type="email"
+              placeholder="请输入邮箱"
+              value={email}
+              onChange={(e) => setEmail(e.target.value)}
+              required
+              disabled={isLoading}
+            />
+          </div>
+          <div className="space-y-2">
+            <Label htmlFor="password">密码</Label>
+            <Input
+              id="password"
+              type="password"
+              placeholder="请输入密码"
+              value={password}
+              onChange={(e) => setPassword(e.target.value)}
+              required
+              disabled={isLoading}
+            />
+          </div>
+          <Button type="submit" className="w-full" disabled={isLoading}>
+            {isLoading ? (
+              <>
+                <Spinner size="sm" className="mr-2" />
+                登录中...
+              </>
+            ) : (
+              '登录'
+            )}
+          </Button>
+        </form>
+      </CardContent>
+    </Card>
+  )
+}
+
+function LoginLoading() {
+  return (
+    <Card className="w-full max-w-md">
+      <CardHeader className="text-center">
+        <CardTitle className="text-2xl">Meme Studio</CardTitle>
+        <CardDescription>谐音梗小游戏运营平台</CardDescription>
+      </CardHeader>
+      <CardContent className="flex justify-center py-8">
+        <Spinner size="lg" />
+      </CardContent>
+    </Card>
+  )
+}
+
+export default function LoginPage() {
+  return (
+    <div className="min-h-screen flex items-center justify-center bg-gray-50 px-4">
+      <Suspense fallback={<LoginLoading />}>
+        <LoginForm />
+      </Suspense>
+    </div>
+  )
+}