feat: 操作日志系统 + 日期修复 + 协同去重 + 主题持久化 + 计划自动完成

本次累积提交包含以下功能：

1. 修复：el-date-picker 缺失 value-format 导致日期保存偏移（8处）
2. 新增：协同拜访 visit_group_id 去重机制（完整副本 + 周报合并 + 亮灯去重）
3. 新增：计划自动完成（创建计划检测已有拜访 / 编辑拜访触发）
4. 新增：拜访表单选择客户后自动预填过期计划内容
5. 新增：移动端主题切换按钮 + 后端持久化
6. 新增：操作日志系统 (audit_logs)，全覆盖 8 个模块 CRUD
7. 新增：PC端「我的数据」支局长/领导视角客户经理列

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

frontend/src/components/DesktopLayout.vue

@@ -48,6 +48,7 @@ const menuGroups = computed<MenuGroup[]>(() => {
   })
   if (auth.isDirector) {
     groups[groups.length - 1].items.push(
+      { path: '/audit-log', label: '操作日志', icon: '<polyline points="9 11 12 14 22 4"></polyline><path d="M21 12v7a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2V5a2 2 0 0 1 2-2h11"></path>' },
       { path: '/users', label: '用户管理', icon: '<path d="M17 21v-2a4 4 0 0 0-4-4H5a4 4 0 0 0-4 4v2"></path><circle cx="9" cy="7" r="4"></circle><path d="M23 21v-2a4 4 0 0 0-3-3.87"></path><path d="M16 3.13a4 4 0 0 1 0 7.75"></path>' },
       { path: '/settings', label: '系统设置', icon: '<circle cx="12" cy="12" r="3"></circle><path d="M19.4 15a1.65 1.65 0 0 0 .33 1.82l.06.06a2 2 0 0 1 0 2.83 2 2 0 0 1-2.83 0l-.06-.06a1.65 1.65 0 0 0-1.82-.33 1.65 1.65 0 0 0-1 1.51V21a2 2 0 0 1-2 2 2 2 0 0 1-2-2v-.09A1.65 1.65 0 0 0 9 19.4a1.65 1.65 0 0 0-1.82.33l-.06.06a2 2 0 0 1-2.83 0 2 2 0 0 1 0-2.83l.06-.06A1.65 1.65 0 0 0 4.68 15a1.65 1.65 0 0 0-1.51-1H3a2 2 0 0 1-2-2 2 2 0 0 1 2-2h.09A1.65 1.65 0 0 0 4.6 9a1.65 1.65 0 0 0-.33-1.82l-.06-.06a2 2 0 0 1 0-2.83 2 2 0 0 1 2.83 0l.06.06A1.65 1.65 0 0 0 9 4.68a1.65 1.65 0 0 0 1-1.51V3a2 2 0 0 1 2-2 2 2 0 0 1 2 2v.09a1.65 1.65 0 0 0 1 1.51 1.65 1.65 0 0 0 1.82-.33l.06-.06a2 2 0 0 1 2.83 0 2 2 0 0 1 0 2.83l-.06.06A1.65 1.65 0 0 0 19.4 9a1.65 1.65 0 0 0 1.51 1H21a2 2 0 0 1 2 2 2 2 0 0 1-2 2h-.09a1.65 1.65 0 0 0-1.51 1z"></path>' },
     )

frontend/src/components/MobileLayout.vue

@@ -2,10 +2,17 @@
 import { useRoute, useRouter } from 'vue-router'
 import { computed } from 'vue'
 import { useAuthStore } from '@/stores/auth'
+import { useThemeStore, themeLabels } from '@/stores/theme'
 
 const route = useRoute()
 const router = useRouter()
 const auth = useAuthStore()
+const themeStore = useThemeStore()
+
+function cycleTheme() {
+  const next = themeStore.currentTheme === 'editorial' ? 'light' : 'editorial'
+  themeStore.setTheme(next)
+}
 
 const tabs = [
   { path: '/m', label: '首页', icon: 'home' },
@@ -33,6 +40,22 @@ const activeTab = computed(() => {
         <div class="header-rule"></div>
       </div>
       <div class="header-actions">
+        <button class="header-pc-btn" @click="cycleTheme" :title="'切换至' + themeLabels[themeStore.currentTheme === 'editorial' ? 'light' : 'editorial']">
+          <svg v-if="themeStore.currentTheme === 'editorial'" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+            <circle cx="12" cy="12" r="5"></circle>
+            <line x1="12" y1="1" x2="12" y2="3"></line>
+            <line x1="12" y1="21" x2="12" y2="23"></line>
+            <line x1="4.22" y1="4.22" x2="5.64" y2="5.64"></line>
+            <line x1="18.36" y1="18.36" x2="19.78" y2="19.78"></line>
+            <line x1="1" y1="12" x2="3" y2="12"></line>
+            <line x1="21" y1="12" x2="23" y2="12"></line>
+            <line x1="4.22" y1="19.78" x2="5.64" y2="18.36"></line>
+            <line x1="18.36" y1="5.64" x2="19.78" y2="4.22"></line>
+          </svg>
+          <svg v-else width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+            <path d="M21 12.79A9 9 0 1 1 11.21 3 7 7 0 0 0 21 12.79z"></path>
+          </svg>
+        </button>
         <button class="header-pc-btn" @click="router.push('/')" title="PC版">
           <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
             <rect x="2" y="3" width="20" height="14" rx="2" ry="2"></rect>