build(android): 压缩生产包体积至 13MB 并统一双渠道产物

生产包九成体积是两套 ABI 的引擎与快照。release 固定 split-debug-info 与
dart-obfuscation，快照从 8MB 降到 1.1MB/ABI；原生库改为压缩存储；开启
R8 裁剪并补保号规则；只打包实际引用的登录背景，移除零引用的图标字体。

pubspec.lock

@@ -105,14 +105,6 @@ packages:
       url: "https://pub.flutter-io.cn"
     source: hosted
     version: "1.0.2"
-  cupertino_icons:
-    dependency: "direct main"
-    description:
-      name: cupertino_icons
-      sha256: "41e005c33bd814be4d3096aff55b1908d419fde52ca656c8c47719ec745873cd"
-      url: "https://pub.flutter-io.cn"
-    source: hosted
-    version: "1.0.9"
   dio:
     dependency: "direct main"
     description: