perf(dashboard): 仪表盘加载提速

- models-dev 快照移出主 bundle（1.35MB→515KB），改为 /models-dev.json 运行时异步加载，就绪后重渲染
- Rust 启动时后台预热价格索引（warm_price_index），首次 get_summary 不再卡
- get_summary 扫描结果 8s TTL 缓存（按 home），切 tab/改范围复用；刷新按钮 refresh=true 强制重扫

src/App.tsx

@@ -1,4 +1,4 @@
-import { useCallback, useEffect, useMemo, useState } from "react";
+import { useCallback, useEffect, useMemo, useReducer, useState } from "react";
 import { invoke } from "@tauri-apps/api/core";
 import { getCurrentWindow } from "@tauri-apps/api/window";
 import { useConfig } from "./hooks/useConfig";
@@ -12,7 +12,7 @@ import { UsageConfigModal } from "./components/UsageConfigModal";
 import { PresetPickerModal } from "./components/PresetPickerModal";
 import { useTranslation } from "./i18n";
 import { getDefaultMaxContextSize } from "./lib/model-defaults";
-import { getModelRef } from "./lib/models-dev";
+import { getModelRef, modelsDevReady, onModelsDevReady } from "./lib/models-dev";
 import {
   presetToProviderAndModels,
   type ProviderPreset,
@@ -121,6 +121,14 @@ export default function App() {
     }).catch(() => {});
   }, [loading, config, agent]);
 
+  // Load the models.dev index in the background (not in the main bundle)
+  // and re-render once it lands so context/capability columns fill in.
+  const [, forceModelsDevReady] = useReducer((x: number) => x + 1, 0);
+  useEffect(() => {
+    onModelsDevReady(forceModelsDevReady);
+    void modelsDevReady();
+  }, []);
+
   const providers = useMemo(
     () => (config ? Object.values(config.providers) : []),
     [config]