chore(frontend): bundle analyzer via npm run analyze (B4)

frontend/vite.config.ts

@@ -2,6 +2,7 @@ import react from "@vitejs/plugin-react";
 import { VitePWA } from "vite-plugin-pwa";
 import tailwindcss from "@tailwindcss/vite";
 import { defineConfig } from "vite";
+import { visualizer } from "rollup-plugin-visualizer";
 
 export default defineConfig({
   resolve: { alias: { "@": "/src" } },
@@ -46,6 +47,10 @@ export default defineConfig({
         ],
       },
     }),
+    // npm run analyze：体积报告输出到 dist-stats/（git-ignore，不进发布产物）
+    ...(process.env.ANALYZE
+      ? [visualizer({ filename: "dist-stats/stats.html", gzipSize: true, brotliSize: true })]
+      : []),
   ],
   server: { proxy: { "/api": process.env.VITE_PROXY_TARGET ?? "http://localhost:8080" } },
 });