werewolf(pwa): 离线 PWA — 自定义 SW 预缓存 + 全屏进度条，牌图 21M→2.8M

- vite-plugin-pwa(injectManifest)自定义 SW：install 逐个抓取并向页面广播进度，
  cache-first 服务，导航离线回退 index.html，缓存版本随清单哈希自动淘汰旧缓存
- 全屏 modal 进度条（src/pwa.ts），反映首屏预缓存真实下载进度
- 牌图 mozjpeg 压缩 + 限长边 900px，每张 ≤200K（21.2MB→2.8MB）
- 生成 PWA 图标 + manifest + apple-touch meta，index.html 接入
- 新增脚本：npm run gen:icons / compress:images

apps/werewolf/frontend/package.json

@@ -7,15 +7,19 @@
     "dev": "vite",
     "build": "vue-tsc -b && vite build",
     "preview": "vite preview",
-    "test": "vitest"
+    "test": "vitest",
+    "gen:icons": "node scripts/gen-icons.mjs",
+    "compress:images": "node scripts/compress-images.mjs"
   },
   "dependencies": {
     "vue": "^3.5.13"
   },
   "devDependencies": {
     "@vitejs/plugin-vue": "^5.2.1",
+    "sharp": "^0.34.5",
     "typescript": "~5.7.2",
     "vite": "^6.0.5",
+    "vite-plugin-pwa": "^1.3.0",
     "vitest": "^2.1.8",
     "vue-tsc": "^2.2.0"
   }