feat: 全部页面添加 MonthPicker 月份切换

新增 MonthPicker 的页面(6个):
- CostPage: 成本与库存管理
- SKUPage: 商品SKU管理
- PlatformPage: 平台与优惠管理
- MemberPage: 会员与复购管理
- SiteSelectionPage: 门店选址分析
- DataQualityPage: 数据质量看板

容器+子组件添加 MonthPicker(2个页面, 11个子组件):
- StoreExpensePage: 门店营业费用分析(10个子组件全部传month)
- CostAnalysisPage/StoreTab: 门店成本tab

跳过(后端不支持month参数):
- RiskPage: 风险管理(全量视图, 不按月过滤)
- TimePage: 时间段分析(全量视图, 不按月过滤)

client/src/components/store-expense/ExpenseOverviewTab.tsx

@@ -8,9 +8,9 @@ import { BarChart, Bar, XAxis, YAxis, CartesianGrid, Tooltip, ResponsiveContaine
 
 const PIE_COLORS = ['#3b82f6', '#ef4444', '#22c55e', '#f97316', '#eab308', '#8b5cf6', '#06b6d4', '#ec4899', '#84cc16', '#a3a3a3', '#f43f5e', '#6366f1', '#14b8a6', '#facc15', '#7c3aed', '#10b981', '#fb923c']
 
-export function ExpenseOverviewTab() {
-  const { data: overview, isLoading: l1 } = useQuery({ queryKey: ['se/overview'], queryFn: () => api.get('/store-expense/overview') })
-  const { data: structure, isLoading: l2 } = useQuery({ queryKey: ['se/structure'], queryFn: () => api.get('/store-expense/expense-structure') })
+export function ExpenseOverviewTab({ month }: { month: string }) {
+  const { data: overview, isLoading: l1 } = useQuery({ queryKey: ['se/overview', month], queryFn: () => api.get('/store-expense/overview', { params: { month } }) })
+  const { data: structure, isLoading: l2 } = useQuery({ queryKey: ['se/structure', month], queryFn: () => api.get('/store-expense/expense-structure', { params: { month } }) })
 
   if (l1 || l2) return <LoadingSpinner text="加载费用总览..." />