修复 CI: 适配 MobileCityPicker 测试断言 + 清理 f-string 和无用 import

- removedMonitorRunwayTabs.test.ts: 检查 MobileCityPicker 替代旧 scan-mobile-city-list-view
- stableServerRefreshPolicy.test.ts: 同上，MobileCityPicker 替代旧视图标识
- scan_forum_topics.py: 移除无占位符的 f-string 和无用 json import

frontend/components/dashboard/scan-terminal/__tests__/removedMonitorRunwayTabs.test.ts

@@ -44,9 +44,9 @@ export function runTests() {
   );
   assert(
     shellPartsSource.includes('"city-list"') &&
-      dashboardSource.includes("scan-mobile-city-list-view") &&
+      dashboardSource.includes("MobileCityPicker") &&
       dashboardSource.includes('setActiveView("city-list")'),
-    "mobile web should expose the lightweight city-list entry view",
+    "mobile web should expose the city-list view via MobileCityPicker",
   );
   assert(
     !dashboardSource.includes('setActiveView("monitor")') &&