fix: 修复 rebase 后重复 clearBrandImage 声明 + 测试加 dismissDialog

- 删除 MyDiary.vue 重复的 clearBrandImage 函数（rebase 遗留）
- 测试加 dismissDialog() 关闭 CI 中 API 错误弹出的 dialog

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/views/MyDiary.vue

@@ -574,26 +574,6 @@ async function clearBrandImage(type) {
   }
 }
 
-async function clearBrandImage(type) {
-  const fieldMap = { logo: 'brand_logo', bg: 'brand_bg', qr: 'qr_code' }
-  const field = fieldMap[type]
-  if (!field) return
-  try {
-    const res = await api('/api/brand', {
-      method: 'PUT',
-      body: JSON.stringify({ [field]: '' }),
-    })
-    if (res.ok) {
-      if (type === 'logo') brandLogo.value = ''
-      else if (type === 'bg') brandBg.value = ''
-      else if (type === 'qr') brandQrImage.value = ''
-      ui.showToast('已清除')
-    }
-  } catch {
-    ui.showToast('清除失败')
-  }
-}
-
 // Account
 async function updateDisplayName() {
   try {