feat: 信息架构重组 + 变更追踪 + 图片预览增强

- 信息架构重组: 周报精简为拜访+纪要两个Tab，工作计划/商机/要客独立为侧边栏「工作」分组下的独立页面
- 侧边栏分组: 汇总/工作/管理三层分组，仪表盘四卡可点击跳转
- 变更追踪(edit_log): 5张表新增JSONB edit_log列，POST创建/PUT diff自动记录，编辑弹窗变更时间轴，表格🕐编辑标记
- 图片预览增强: ImagePreview统一组件，支持适应页面/缩放/拖拽平移/滚轮缩放/键盘快捷键
- 修复客户导入500错误(errors变量未初始化)
- 移除工作计划/商机/要客页面冗余编辑按钮

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

frontend/src/views/mobile/VisitForm.vue

@@ -7,6 +7,8 @@ import { visitsApi } from '@/api/visits'
 import { customersApi } from '@/api/customers'
 import { uploadApi } from '@/api/upload'
 import { useAuthStore } from '@/stores/auth'
+import ImagePreview from '@/components/ImagePreview.vue'
+import EditLogPanel from '@/components/EditLogPanel.vue'
 import api from '@/api/index'
 
 const router = useRouter()
@@ -344,15 +346,10 @@ async function handleDelete() {
           删除
         </button>
       </div>
+      <EditLogPanel v-if="isEdit" :edit-log="form.edit_log || []" />
     </el-form>
 
-    <!-- Image Preview Dialog -->
-    <teleport to="body">
-      <div v-if="previewDialogVisible" class="image-preview-overlay" @click="previewDialogVisible = false">
-        <img :src="previewImageUrl" class="image-preview-full" @click.stop />
-        <button class="image-preview-close" @click="previewDialogVisible = false">✕</button>
-      </div>
-    </teleport>
+    <ImagePreview v-model="previewDialogVisible" :image-url="previewImageUrl" />
   </div>
 </template>