feat(export): add coverageItems export formatting and adjust column order

1. 新增覆盖地市字段的导出格式化逻辑，将后端返回的「省份|城市，省份|城市」格式转为「省份-城市、省份-城市」
2. 调整渠道导出列的顺序，将市字段移到正确位置并加入默认导出字段

frontend/nginx/default.conf.template

@@ -7,6 +7,20 @@ server {
 
     resolver ${RESOLVER} valid=30s ipv6=off;
 
+    # 静态资源：命中直接返回文件并长时间缓存；缺失返回 404，绝不回退成 HTML，
+    # 避免 CDN/网关把误回退的 index.html 当资源缓存造成 MIME 报错。
+    location /assets/ {
+        try_files $uri =404;
+        expires 1y;
+        add_header Cache-Control "public, max-age=31536000, immutable";
+        access_log off;
+    }
+
+    # index.html 不缓存，保证每次回源拿到最新 hash 引用。
+    location = /index.html {
+        add_header Cache-Control "no-cache";
+    }
+
     location / {
         try_files $uri $uri/ /index.html;
     }

frontend/src/pages/Expansion.tsx

@@ -99,6 +99,7 @@ type ChannelExportFieldKey =
   | "province"
   | "city"
   | "officeAddress"
+  | "coverageItems"
   | "certificationLevel"
   | "channelIndustry"
   | "channelAttribute"
@@ -387,6 +388,23 @@ function normalizeExportText(value?: string | number | boolean | null) {
   return normalized;
 }
 
+// 后端 coverageItems 形如「省份|城市，省份|城市」，导出时转为「省份-城市、省份-城市」。
+function formatCoverageItemsExport(value?: string) {
+  if (!value?.trim()) {
+    return "";
+  }
+  return value
+    .split("，")
+    .map((part) => {
+      const [province, city] = part.split("|");
+      const p = province?.trim() || "";
+      const c = city?.trim() || "";
+      return c ? `${p}-${c}` : p;
+    })
+    .filter(Boolean)
+    .join("、");
+}
+
 function normalizeExportNumber(value?: string | number | null) {
   if (value === null || value === undefined) {
     return undefined;
@@ -824,7 +842,9 @@ function buildChannelExportColumns(isOptions: ExpansionDictOption[]): Array<Expo
   return [
   { key: "name", label: "渠道名称", value: (item) => normalizeExportText(item.name) },
   { key: "province", label: "省份", value: (item) => normalizeExportText(item.province) },
+  { key: "city", label: "市", value: (item) => normalizeExportText(item.city) },
   { key: "officeAddress", label: "办公地址", kind: "longText", value: (item) => normalizeExportText(item.officeAddress) },
+  { key: "coverageItems", label: "覆盖地市", value: (item) => formatCoverageItemsExport(item.coverageItems) },
   { key: "channelIndustry", label: "聚焦行业", value: (item) => normalizeExportText(item.channelIndustry) },
   { key: "certificationLevel", label: "汇智内部认证级别", value: (item) => normalizeExportText(item.certificationLevel) },
   { key: "channelAttribute", label: "渠道属性", value: (item) => normalizeExportText(item.channelAttribute) },
@@ -839,7 +859,6 @@ function buildChannelExportColumns(isOptions: ExpansionDictOption[]): Array<Expo
   { key: "contacts", label: "人员信息", kind: "contact", value: (item) => formatExportContactListCell(item.contacts, wecomLabelByValue) },
   { key: "followUps", label: "跟进记录", kind: "followup", value: (item) => formatExportFollowUps(item.followUps) },
   { key: "channelCode", label: "编码", value: (item) => normalizeExportText(item.channelCode) },
-  { key: "city", label: "市", value: (item) => normalizeExportText(item.city) },
   { key: "relatedProjectAmount", label: "跟进项目金额", numFmt: "#,##0.00", value: (item) => sumRelatedProjectAmount(item.relatedProjects) ?? "" },
   { key: "notes", label: "备注说明", kind: "longText", value: (item) => normalizeExportText(item.notes) },
   { key: "owner", label: "创建人", value: (item) => normalizeExportText(item.owner) },
@@ -851,6 +870,7 @@ function buildChannelExportColumns(isOptions: ExpansionDictOption[]): Array<Expo
 const defaultChannelExportFields: ChannelExportFieldKey[] = [
   "name",
   "province",
+  "city",
   "officeAddress",
   "channelIndustry",
   "certificationLevel",