build: vendor pinned flutter_vless Android runtime (#10)

Replace build-time pub-cache mutation with a repository-owned pinned runtime so reviewed native source is the source compiled into the app.

pubspec.lock

@@ -172,12 +172,11 @@ packages:
     source: hosted
     version: "1.1.5"
   flutter_vless_android:
-    dependency: transitive
+    dependency: "direct overridden"
     description:
-      name: flutter_vless_android
-      sha256: "5e6fe73d3606ed8c73e87fac15efa7631e12ce18d39a4bd4e13b6c097c6d52b9"
-      url: "https://pub.dev"
-    source: hosted
+      path: "local_packages/flutter_vless_android-1.1.5"
+      relative: true
+    source: path
     version: "1.1.5"
   flutter_vless_macos:
     dependency: transitive