feat: 注册、重置密码、重发验证邮件添加验证码功能

后端修改：
- 添加通用验证码验证函数 verifyCaptcha()
- /api/register 接口添加验证码验证
- /api/password/forgot 接口添加验证码验证
- /api/resend-verification 接口添加验证码验证

前端修改：
- 注册表单添加验证码输入框和图片
- 忘记密码模态框添加验证码
- 重发验证邮件区域添加验证码输入
- 添加各表单的验证码刷新方法
- 提交失败后自动刷新验证码

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/app.js

@@ -29,8 +29,10 @@ createApp({
       registerForm: {
         username: '',
         email: '',
-        password: ''
+        password: '',
+        captcha: ''
       },
+      registerCaptchaUrl: '',
 
       // 验证码相关
       showCaptcha: false,
@@ -125,8 +127,10 @@ createApp({
       // 忘记密码
       showForgotPasswordModal: false,
       forgotPasswordForm: {
-        email: ''
+        email: '',
+        captcha: ''
       },
+      forgotPasswordCaptchaUrl: '',
       showResetPasswordModal: false,
       resetPasswordForm: {
         token: '',
@@ -134,6 +138,8 @@ createApp({
       },
       showResendVerify: false,
       resendVerifyEmail: '',
+      resendVerifyCaptcha: '',
+      resendVerifyCaptchaUrl: '',
 
       // 系统设置
       systemSettings: {
@@ -604,18 +610,37 @@ handleDragLeave(e) {
       }
     },
 
-    // 刷新验证码
+    // 刷新验证码（登录）
     refreshCaptcha() {
       this.captchaUrl = `${this.apiBase}/api/captcha?t=${Date.now()}`;
     },
 
+    // 刷新注册验证码
+    refreshRegisterCaptcha() {
+      this.registerCaptchaUrl = `${this.apiBase}/api/captcha?t=${Date.now()}`;
+    },
+
+    // 刷新忘记密码验证码
+    refreshForgotPasswordCaptcha() {
+      this.forgotPasswordCaptchaUrl = `${this.apiBase}/api/captcha?t=${Date.now()}`;
+    },
+
+    // 刷新重发验证邮件验证码
+    refreshResendVerifyCaptcha() {
+      this.resendVerifyCaptchaUrl = `${this.apiBase}/api/captcha?t=${Date.now()}`;
+    },
+
     async resendVerification() {
       if (!this.resendVerifyEmail) {
         this.showToast('error', '错误', '请输入邮箱或用户名后再重试');
         return;
       }
+      if (!this.resendVerifyCaptcha) {
+        this.showToast('error', '错误', '请输入验证码');
+        return;
+      }
       try {
-        const payload = {};
+        const payload = { captcha: this.resendVerifyCaptcha };
         if (this.resendVerifyEmail.includes('@')) {
           payload.email = this.resendVerifyEmail;
         } else {
@@ -624,10 +649,17 @@ handleDragLeave(e) {
         const response = await axios.post(`${this.apiBase}/api/resend-verification`, payload);
         if (response.data.success) {
           this.showToast('success', '成功', '验证邮件已发送，请查收');
+          this.showResendVerify = false;
+          this.resendVerifyEmail = '';
+          this.resendVerifyCaptcha = '';
+          this.resendVerifyCaptchaUrl = '';
         }
       } catch (error) {
         console.error('重发验证邮件失败:', error);
         this.showToast('error', '错误', error.response?.data?.message || '发送失败');
+        // 刷新验证码
+        this.resendVerifyCaptcha = '';
+        this.refreshResendVerifyCaptcha();
       }
     },
 
@@ -661,8 +693,10 @@ handleDragLeave(e) {
           this.registerForm = {
             username: '',
             email: '',
-            password: ''
+            password: '',
+            captcha: ''
           };
+          this.registerCaptchaUrl = '';
         }
       } catch (error) {
         const errorData = error.response?.data;
@@ -671,6 +705,9 @@ handleDragLeave(e) {
         } else {
           this.errorMessage = errorData?.message || '注册失败';
         }
+        // 刷新验证码
+        this.registerForm.captcha = '';
+        this.refreshRegisterCaptcha();
       }
     },
 
@@ -1881,6 +1918,10 @@ handleDragLeave(e) {
         this.showToast('error', '错误', '请输入注册邮箱');
         return;
       }
+      if (!this.forgotPasswordForm.captcha) {
+        this.showToast('error', '错误', '请输入验证码');
+        return;
+      }
 
       try {
         const response = await axios.post(
@@ -1891,11 +1932,15 @@ handleDragLeave(e) {
         if (response.data.success) {
           this.showToast('success', '成功', '如果邮箱存在，将收到重置邮件');
           this.showForgotPasswordModal = false;
-          this.forgotPasswordForm = { email: '' };
+          this.forgotPasswordForm = { email: '', captcha: '' };
+          this.forgotPasswordCaptchaUrl = '';
         }
       } catch (error) {
         console.error('提交密码重置请求失败:', error);
         this.showToast('error', '错误', error.response?.data?.message || '提交失败');
+        // 刷新验证码
+        this.forgotPasswordForm.captcha = '';
+        this.refreshForgotPasswordCaptcha();
       }
     },