feat: 移动端导航重构 — 4 Tab + 工作中心 + 模块列表

- TabBar 新增「工作」标签（首页/工作/拜访/纪要）
- 新增工作中心页（/m/work），四卡片入口显示各模块记录数
- 新增三个列表页：工作计划/商机跟单/要客拜访（卡片流+删除）
- 首页精简：移除快捷 chip，入口统一到工作中心
- 路由新增: /m/work, /m/plans, /m/mini-biz, /m/key-visits

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

frontend/src/components/MobileLayout.vue

@@ -8,25 +8,15 @@ const router = useRouter()
 const auth = useAuthStore()
 
 const tabs = [
-  {
-    path: '/m',
-    label: '首页',
-    icon: 'home',
-  },
-  {
-    path: '/m/visit/new',
-    label: '拜访',
-    icon: 'visit',
-  },
-  {
-    path: '/m/note/new',
-    label: '纪要',
-    icon: 'note',
-  },
+  { path: '/m', label: '首页', icon: 'home' },
+  { path: '/m/work', label: '工作', icon: 'work' },
+  { path: '/m/visit/new', label: '拜访', icon: 'visit' },
+  { path: '/m/note/new', label: '纪要', icon: 'note' },
 ]
 
 const activeTab = computed(() => {
   if (route.path === '/m') return '/m'
+  if (route.path === '/m/work' || route.path.startsWith('/m/plans') || route.path.startsWith('/m/mini-biz') || route.path.startsWith('/m/key-visits') || route.path.startsWith('/m/leaves') || route.path.startsWith('/m/leave')) return '/m/work'
   if (route.path.includes('/visit')) return '/m/visit/new'
   if (route.path.includes('/note')) return '/m/note/new'
   return route.path
@@ -76,6 +66,11 @@ const activeTab = computed(() => {
             <path d="M3 9l9-7 9 7v11a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2z"></path>
             <polyline points="9 22 9 12 15 12 15 22"></polyline>
           </svg>
+          <!-- Work icon -->
+          <svg v-else-if="tab.icon === 'work'" class="tab-icon" width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round">
+            <rect x="2" y="7" width="20" height="14" rx="2" ry="2"></rect>
+            <path d="M16 21V5a2 2 0 0 0-2-2h-4a2 2 0 0 0-2 2v16"></path>
+          </svg>
           <!-- Visit icon -->
           <svg v-else-if="tab.icon === 'visit'" class="tab-icon" width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round">
             <path d="M16 4h2a2 2 0 0 1 2 2v14a2 2 0 0 1-2 2H6a2 2 0 0 1-2-2V6a2 2 0 0 1 2-2h2"></path>