[feat]:[FL-117][增加无账号用户注册功能]

- 新增用户注册页面 /register
- 在登录页面添加注册入口链接
- 支持邮箱、用户名、密码注册
- 包含密码确认和前端验证

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: multica-agent <github@multica.ai>

web/src/app/login/page.tsx

@@ -146,6 +146,13 @@ export default function LoginPage() {
           </form>
 
           {error && <Alert showIcon type="error" message={error} />}
+
+          <div className="text-center">
+            <Typography.Text type="secondary">
+              没有账号？{" "}
+              <Typography.Link href="/register">立即注册</Typography.Link>
+            </Typography.Text>
+          </div>
         </Space>
       </Card>
     </main>

web/src/app/register/page.tsx

@@ -0,0 +1,154 @@
+"use client";
+
+import { IdcardOutlined, LockOutlined, MailOutlined, UserOutlined } from "@ant-design/icons";
+import { ChangeEvent, FormEvent, useEffect, useState } from "react";
+import { useRouter } from "next/navigation";
+import { Alert, Button, Input, Space, Typography } from "antd";
+
+import { useAuth } from "@/components/auth-provider";
+import { Card } from "@/components/ui-antd";
+import { withBasePath } from "@/lib/base-path";
+
+export default function RegisterPage() {
+  const router = useRouter();
+  const { user, initializing, register } = useAuth();
+
+  const [email, setEmail] = useState("");
+  const [username, setUsername] = useState("");
+  const [password, setPassword] = useState("");
+  const [confirmPassword, setConfirmPassword] = useState("");
+  const [busy, setBusy] = useState(false);
+  const [error, setError] = useState("");
+
+  useEffect(() => {
+    if (!initializing && user) {
+      router.replace("/users");
+    }
+  }, [initializing, router, user]);
+
+  const handleSubmit = async (event: FormEvent<HTMLFormElement>) => {
+    event.preventDefault();
+    setError("");
+
+    if (password !== confirmPassword) {
+      setError("两次输入的密码不一致");
+      return;
+    }
+
+    if (password.length < 8) {
+      setError("密码长度至少为 8 个字符");
+      return;
+    }
+
+    setBusy(true);
+
+    try {
+      await register(email, username, password);
+    } catch (submitError) {
+      const message = submitError instanceof Error ? submitError.message : "未知错误";
+      setError(message);
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  if (initializing) {
+    return (
+      <main className="mx-auto flex min-h-screen w-full max-w-3xl items-center justify-center px-6 py-20">
+        <Typography.Text type="secondary">正在初始化会话...</Typography.Text>
+      </main>
+    );
+  }
+
+  if (user) {
+    return (
+      <main className="mx-auto flex min-h-screen w-full max-w-3xl items-center justify-center px-6 py-20">
+        <Typography.Text type="secondary">正在跳转到控制台...</Typography.Text>
+      </main>
+    );
+  }
+
+  return (
+    <main className="flex min-h-screen items-center justify-center bg-[var(--fquiz-theme-bg-layout)] px-4 py-8">
+      <Card className="w-full max-w-[400px]">
+        <Space direction="vertical" size={20} className="w-full">
+          <div className="flex justify-center">
+            <img
+              src={withBasePath("/favicon.ico")}
+              alt="高压电塔图标"
+              width={72}
+              height={72}
+              className="h-[72px] w-[72px]"
+            />
+          </div>
+
+          <Typography.Title level={3} className="!mb-0 !text-center">
+            用户注册
+          </Typography.Title>
+
+          <form className="space-y-4" onSubmit={handleSubmit}>
+            <Input
+              size="large"
+              value={email}
+              prefix={<MailOutlined />}
+              placeholder="邮箱"
+              type="email"
+              onChange={(event: ChangeEvent<HTMLInputElement>) => setEmail(event.currentTarget.value)}
+              autoComplete="email"
+              required
+            />
+
+            <Input
+              size="large"
+              value={username}
+              prefix={<UserOutlined />}
+              placeholder="用户名（3-64 个字符）"
+              onChange={(event: ChangeEvent<HTMLInputElement>) => setUsername(event.currentTarget.value)}
+              autoComplete="username"
+              minLength={3}
+              maxLength={64}
+              required
+            />
+
+            <Input.Password
+              size="large"
+              value={password}
+              prefix={<LockOutlined />}
+              placeholder="密码（至少 8 个字符）"
+              onChange={(event: ChangeEvent<HTMLInputElement>) => setPassword(event.currentTarget.value)}
+              autoComplete="new-password"
+              minLength={8}
+              maxLength={128}
+              required
+            />
+
+            <Input.Password
+              size="large"
+              value={confirmPassword}
+              prefix={<LockOutlined />}
+              placeholder="确认密码"
+              onChange={(event: ChangeEvent<HTMLInputElement>) => setConfirmPassword(event.currentTarget.value)}
+              autoComplete="new-password"
+              minLength={8}
+              maxLength={128}
+              required
+            />
+
+            <Button block size="large" type="primary" htmlType="submit" loading={busy}>
+              注册
+            </Button>
+          </form>
+
+          {error && <Alert showIcon type="error" message={error} />}
+
+          <div className="text-center">
+            <Typography.Text type="secondary">
+              已有账号？{" "}
+              <Typography.Link href="/login">立即登录</Typography.Link>
+            </Typography.Text>
+          </div>
+        </Space>
+      </Card>
+    </main>
+  );
+}