pointer_lock: declare android, ios, windows and linux so pub.dev lists them #80

pointer_lock 0.4.2 declares only macos under flutter.plugin.platforms. The web is handled by a conditional export, and every other native target already falls through to MethodChannelPointerLock, whose isSupported is false off macOS (pointer_lock_method_channel.dart:28). So at runtime the package already works everywhere: it locks on macOS and on the web, and elsewhere it says it can't.

pub.dev only reads the pubspec, though, so it lists pointer_lock for macOS alone. Every package that depends on it gets the same listing. For voxel_game 0.4.0-dev, pub.dev's report says Android, iOS, Windows and Linux are "blocked by the pointer_lock package", and its platform tags hold platform:macos only. The kit runs on all five and draws touch controls on phones. Its other packages, which don't depend on pointer_lock, are listed for all five.

The ask: declare android, ios, windows and linux with a Dart-only implementation, for example:

flutter:
  plugin:
    platforms:
      macos:
        pluginClass: PointerLockPlugin
      android:
        dartPluginClass: PointerLockUnsupported
      ios:
        dartPluginClass: PointerLockUnsupported
      windows:
        dartPluginClass: PointerLockUnsupported
      linux:
        dartPluginClass: PointerLockUnsupported

PointerLockUnsupported.registerWith() would set PointerLockPlatform.instance to an implementation whose isSupported is false and whose calls are no-ops, the same answers the method channel already gives off macOS. That needs no native code, and once the platforms are declared pub.dev lists them.

I'm happy to open a PR with this and a test, if you'd take one.