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/desktop/Dashboard.vue

@@ -82,7 +82,7 @@ function rowState(p: any): 'full' | 'catching' | 'missing' {
 
     <!-- ═══ Stats Cards ═══ -->
     <div class="stat-grid">
-      <div class="stat-card">
+      <div class="stat-card stat-card--clickable" @click="router.push('/weekly-report')">
         <div class="stat-glyph stat-glyph--ink">
           <svg width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round">
             <path d="M3 9l9-7 9 7v11a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2z"></path>
@@ -94,7 +94,7 @@ function rowState(p: any): 'full' | 'catching' | 'missing' {
           <span class="stat-label">本周拜访</span>
         </div>
       </div>
-      <div class="stat-card">
+      <div class="stat-card stat-card--clickable" @click="router.push('/work-plans')">
         <div class="stat-glyph stat-glyph--sage">
           <svg width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round">
             <rect x="3" y="4" width="18" height="18" rx="2" ry="2"></rect>
@@ -108,7 +108,7 @@ function rowState(p: any): 'full' | 'catching' | 'missing' {
           <span class="stat-label">工作计划</span>
         </div>
       </div>
-      <div class="stat-card">
+      <div class="stat-card stat-card--clickable" @click="router.push('/mini-business')">
         <div class="stat-glyph stat-glyph--gold">
           <svg width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round">
             <line x1="12" y1="1" x2="12" y2="23"></line>
@@ -120,7 +120,7 @@ function rowState(p: any): 'full' | 'catching' | 'missing' {
           <span class="stat-label">商机跟单</span>
         </div>
       </div>
-      <div class="stat-card">
+      <div class="stat-card stat-card--clickable" @click="router.push('/key-visits')">
         <div class="stat-glyph stat-glyph--vermilion">
           <svg width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round">
             <polygon points="12 2 15.09 8.26 22 9.27 17 14.14 18.18 21.02 12 17.77 5.82 21.02 7 14.14 2 9.27 8.91 8.26 12 2"></polygon>
@@ -241,6 +241,8 @@ function rowState(p: any): 'full' | 'catching' | 'missing' {
   transition: all var(--transition);
 }
 .stat-card:hover { box-shadow: var(--shadow-md); }
+.stat-card--clickable { cursor: pointer; }
+.stat-card--clickable:hover { border-color: var(--gold); }
 
 .stat-glyph {
   width: 48px; height: 48px;