feat: 迁移前端构建从 Bun fullstack 到 Vite

前端性能问题根因在于 Bun bundler 无法有效 code split、CSS
tree-shake 和产出优化的前端资源。经多轮 Bun 原生优化尝试
均无明显效果后，决定将前端构建迁回 Vite。

主要变更：

- 前端构建：从 Bun HTML import bundling 切换为 Vite build
  （Rolldown code splitting、vendor chunk、CSS 优化）
- 开发模式：从 Bun fullstack 单进程 HMR 切换为 Vite dev
  server + Bun API server 双进程（:5173 + :3000）
- 生产构建：三步流水线（Vite build → code generation →
  Bun compile），通过 `import with { type: "file" }` 嵌入前端资源
- 静态资源服务：从 Bun HTML import manifest 切换为自定义
  serveStaticAsset 函数，支持 SPA fallback 和正确的 Cache-Control
- Server 接口：BootstrapOptions 和 StartServerOptions 增加
  staticAssets? 可选参数
- 文档更新：DEVELOPMENT.md 和 README.md 反映新的开发模式，
  主 specs 同步 delta 变更

新增能力：
- static-asset-embedding: 构建时资源扫描与 code generation、
  运行时静态资源服务
- vite-frontend-bundling: Vite 构建配置、code splitting 策略、
  CSS 处理

src/server/bootstrap.ts

@@ -2,6 +2,7 @@ import { join } from "node:path";
 
 import type { RuntimeMode } from "../shared/api";
 import type { StartServerOptions } from "./server";
+import type { StaticAssets } from "./static";
 
 import { loadConfig, type ResolvedConfig } from "./checker/config-loader";
 import { ProbeEngine } from "./checker/engine";
@@ -26,6 +27,7 @@ export interface BootstrapDependencies {
 export interface BootstrapOptions {
   configPath: string;
   mode: RuntimeMode;
+  staticAssets?: StaticAssets;
 }
 
 type BootstrapEngine = Pick<ProbeEngine, "start" | "stop">;
@@ -69,6 +71,7 @@ export async function bootstrap(options: BootstrapOptions, dependencies: Bootstr
     serve({
       config: { host: config.host, port: config.port },
       mode: options.mode,
+      staticAssets: options.staticAssets,
       store,
     });
   } catch (error) {

src/server/server.ts

@@ -1,33 +1,36 @@
 import type { RuntimeMode } from "../shared/api";
 import type { ProbeStore } from "./checker/store";
 import type { RuntimeConfig } from "./config";
+import type { StaticAssets } from "./static";
 
-import homepage from "../web/index.html";
 import { createApiError, jsonResponse } from "./helpers";
 import { handleDashboard } from "./routes/dashboard";
 import { handleHealth } from "./routes/health";
 import { handleHistory } from "./routes/history";
 import { handleMeta } from "./routes/meta";
 import { handleMetrics } from "./routes/metrics";
+import { serveStaticAsset } from "./static";
 
 export interface StartServerOptions {
   config: RuntimeConfig;
   mode: RuntimeMode;
+  staticAssets?: StaticAssets;
   store: ProbeStore;
 }
 
 export function startServer(options: StartServerOptions) {
-  const { config, mode, store } = options;
+  const { config, mode, staticAssets, store } = options;
 
   const server = Bun.serve({
-    development: mode === "development" ? { console: true, hmr: true } : false,
-    fetch() {
-      return new Response("Not found", { status: 404 });
+    fetch(req) {
+      if (staticAssets) {
+        return serveStaticAsset(new URL(req.url).pathname, staticAssets);
+      }
+      return new Response("Frontend is served by Vite dev server on :5173", { status: 404 });
     },
     hostname: config.host,
     port: config.port,
     routes: {
-      "/*": homepage,
       "/api/*": () => jsonResponse(createApiError("API route not found", 404), { mode, status: 404 }),
       "/api/dashboard": {
         GET: (req) => handleDashboard(new URL(req.url), store, mode),

src/server/static.ts

@@ -0,0 +1,60 @@
+export interface StaticAssets {
+  files: Record<string, Blob>;
+  indexHtml: Blob;
+}
+
+const CONTENT_TYPES: Record<string, string> = {
+  ".css": "text/css; charset=utf-8",
+  ".html": "text/html; charset=utf-8",
+  ".js": "text/javascript; charset=utf-8",
+  ".json": "application/json; charset=utf-8",
+  ".mjs": "text/javascript; charset=utf-8",
+  ".png": "image/png",
+  ".svg": "image/svg+xml",
+  ".woff": "font/woff",
+  ".woff2": "font/woff2",
+};
+
+export function contentTypeFor(path: string): string {
+  const dot = path.lastIndexOf(".");
+  if (dot === -1) return "application/octet-stream";
+  const ext = path.slice(dot);
+  return CONTENT_TYPES[ext] ?? "application/octet-stream";
+}
+
+export function hasFileExtension(path: string): boolean {
+  const lastSlash = path.lastIndexOf("/");
+  const segment = lastSlash === -1 ? path : path.slice(lastSlash + 1);
+  return segment.includes(".");
+}
+
+export function htmlResponse(html: Blob): Response {
+  return new Response(html, {
+    headers: {
+      "Cache-Control": "no-cache",
+      "Content-Type": "text/html; charset=utf-8",
+    },
+  });
+}
+
+export function serveStaticAsset(pathname: string, assets: StaticAssets): Response {
+  if (pathname === "/") {
+    return htmlResponse(assets.indexHtml);
+  }
+
+  const file = assets.files[pathname];
+  if (file) {
+    return new Response(file, {
+      headers: {
+        "Cache-Control": "public, max-age=31536000, immutable",
+        "Content-Type": contentTypeFor(pathname),
+      },
+    });
+  }
+
+  if (hasFileExtension(pathname)) {
+    return new Response("Not found", { status: 404 });
+  }
+
+  return htmlResponse(assets.indexHtml);
+}