fix: 区域统计客户筛选生效，后端region-stats支持过滤参数

- 后端/region-stats新增customer/city/region查询参数
- 前端regionFilters变化时重新请求后端数据
- 移除前端冗余过滤逻辑，由后端统一处理

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/App.tsx

@@ -236,6 +236,18 @@ export default function App() {
     return () => clearInterval(interval);
   }, [loadData]);
 
+  // Re-fetch region data when filters change
+  useEffect(() => {
+    const hasFilter = regionFilters.customer || regionFilters.city || regionFilters.region;
+    if (hasFilter) {
+      fetchRegionStats({ customer: regionFilters.customer || undefined, city: regionFilters.city || undefined, region: regionFilters.region || undefined })
+        .then(setRegionData).catch(() => {});
+    } else {
+      // No filters: use data from the main loadData cycle
+      fetchRegionStats().then(setRegionData).catch(() => {});
+    }
+  }, [regionFilters]);
+
   // Fetch region chart data when view changes
   useEffect(() => {
     fetchRegionChart(regionChartView, regionChartView === 'city' ? 5 : 8).then(setRegionChartData).catch(() => setRegionChartData([]));
@@ -477,7 +489,7 @@ export default function App() {
   const uniqueModalLocations = useMemo(() => Array.from(new Set(modalVehicles.map(v => v.location).filter(Boolean))), [modalVehicles]);
 
   // Derived data for region section
-  const filteredRegionData = useMemo(() => regionData.filter((r) => !regionFilters.region || r.region === regionFilters.region), [regionData, regionFilters.region]);
+  // regionData is already filtered by backend based on regionFilters
 
   // Filtered modal vehicles based on modal filters
   const filteredModalVehicles = useMemo(() => modalVehicles.filter((v) => {
@@ -2063,7 +2075,7 @@ export default function App() {
                   </tr>
                 </thead>
                 <tbody className="text-xs">
-                  {regionData.filter(r => !regionFilters.region || r.region === regionFilters.region).map((r) => {
+                  {regionData.map((r) => {
                     const isExpanded = expandedRegions.has(r.region);
                     return (
                       <React.Fragment key={r.region}>
@@ -2124,7 +2136,7 @@ export default function App() {
 
             {/* Mobile View (Region) */}
             <div className="lg:hidden p-2 space-y-3">
-              {regionData.filter(r => !regionFilters.region || r.region === regionFilters.region).map((r) => {
+              {regionData.map((r) => {
                 const isExpanded = expandedRegions.has(r.region);
                 return (
                   <div key={r.region} className="bg-slate-50/50 rounded-xl border border-slate-100 overflow-hidden">