feat: 前端对接 Profile/Messages/Settings 页面 API

- 3 消息页 + 2 资料编辑页 + 3 设置页 + 2 资料展示页
- api.ts 新增 Profile/Messages/ChangePassword 等类型和方法
- SSEContext 事件映射修复 + 断线重连修复
- 剩余页面加 USE_MOCK 双模式，52/55 页面已完成

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/app/creator/settings/account/page.tsx

@@ -18,6 +18,9 @@ import { Button } from '@/components/ui/Button'
 import { Input } from '@/components/ui/Input'
 import { Modal } from '@/components/ui/Modal'
 import { cn } from '@/lib/utils'
+import { USE_MOCK } from '@/contexts/AuthContext'
+import { api } from '@/lib/api'
+import { useToast } from '@/components/ui/Toast'
 
 // 模拟登录设备数据
 const mockDevices = [
@@ -108,12 +111,31 @@ function ChangePasswordModal({
     confirmPassword: '',
   })
   const [isSaving, setIsSaving] = useState(false)
+  const toast = useToast()
 
   const handleSubmit = async () => {
+    if (formData.newPassword !== formData.confirmPassword) {
+      toast.error('两次输入的密码不一致')
+      return
+    }
     setIsSaving(true)
-    await new Promise(resolve => setTimeout(resolve, 1500))
-    setIsSaving(false)
-    setStep(2)
+    if (USE_MOCK) {
+      await new Promise(resolve => setTimeout(resolve, 1500))
+      setIsSaving(false)
+      setStep(2)
+      return
+    }
+    try {
+      await api.changePassword({
+        old_password: formData.currentPassword,
+        new_password: formData.newPassword,
+      })
+      setIsSaving(false)
+      setStep(2)
+    } catch (err: any) {
+      setIsSaving(false)
+      toast.error(err.message || '密码修改失败')
+    }
   }
 
   const handleClose = () => {

frontend/app/creator/settings/notification/page.tsx

@@ -2,6 +2,8 @@
 
 import React, { useState } from 'react'
 import { useRouter } from 'next/navigation'
+import { USE_MOCK } from '@/contexts/AuthContext'
+import { api } from '@/lib/api'
 import {
   ArrowLeft,
   Mail,