build: 生产环境构建 (ENV=prod)

- 使用 --dart-define=ENV=prod 参数
- API 指向生产环境: http://8.155.172.147:5010
- 字体 tree-shaking 优化完成
- MaterialIcons 减少 99.5%

flutter_monisuo/build/web/flutter_bootstrap.js

@@ -37,6 +37,6 @@ _flutter.buildConfig = {"engineRevision":"e4b8dca3f1b4ede4c30371002441c88c12187e
 
 _flutter.loader.load({
   serviceWorkerSettings: {
-    serviceWorkerVersion: "1910618382" /* Flutter's service worker is deprecated and will be removed in a future Flutter release. */
+    serviceWorkerVersion: "1306420232" /* Flutter's service worker is deprecated and will be removed in a future Flutter release. */
   }
 });