Remove dashboard prewarm requests

frontend/components/dashboard/PolyWeatherDashboard.tsx

@@ -6,7 +6,6 @@ import {
   DashboardStoreProvider,
   useDashboardStore,
 } from "@/hooks/useDashboardStore";
-import { preloadChartJs } from "@/hooks/useChart";
 import { I18nProvider, useI18n } from "@/hooks/useI18n";
 import { CitySidebar } from "@/components/dashboard/CitySidebar";
 import { DetailPanel } from "@/components/dashboard/DetailPanel";
@@ -82,42 +81,6 @@ function DashboardScreen() {
     };
   }, [store]);
 
-  useEffect(() => {
-    const browserWindow = window as Window & {
-      requestIdleCallback?: (
-        cb: IdleRequestCallback,
-        options?: IdleRequestOptions,
-      ) => number;
-      cancelIdleCallback?: (handle: number) => void;
-    };
-    if (typeof browserWindow.requestIdleCallback === "function") {
-      const handle = browserWindow.requestIdleCallback(() => {
-        void loadHistoryModal();
-        void loadFutureForecastModal();
-      }, { timeout: 1200 });
-      return () => {
-        if (typeof browserWindow.cancelIdleCallback === "function") {
-          browserWindow.cancelIdleCallback(handle);
-        }
-      };
-    }
-
-    const timeoutId = window.setTimeout(() => {
-      void loadHistoryModal();
-      void loadFutureForecastModal();
-    }, 500);
-    return () => {
-      window.clearTimeout(timeoutId);
-    };
-  }, []);
-
-  useEffect(() => {
-    if (!store.selectedCity) return;
-    void preloadChartJs();
-    void loadHistoryModal();
-    void loadFutureForecastModal();
-  }, [store.selectedCity]);
-
   // Avoid full-page flashing on initial load; only show this overlay for manual refresh.
   const showLoading =
     store.loadingState.cities ||