build(metro): add web shims for native React Native API compatibility

Add Metro configuration to resolve native-only React Native APIs with web-compatible shims. This enables packages like react-native-pager-view to work on the web platform by providing shim implementations for codegenNativeComponent, codegenNativeCommands, and CodegenTypes that are unavailable in react-native-web.

Also simplify Android signing configuration in CI by using standard Gradle property names (MYAPP_UPLOAD_*) and remove the build.gradle patching step.

web-shims/react-native/Libraries/Utilities/codegenNativeComponent.js

@@ -0,0 +1,18 @@
+const React = require('react');
+
+function codegenNativeComponent(componentName, options) {
+  const componentNameClean = componentName
+    .replace(/^RNC/, '')
+    .replace(/^RNS/, '')
+    .replace(/^RN/, '');
+
+  const NativeComponent = React.forwardRef((props, ref) => {
+    const { children, ...rest } = props;
+    return React.createElement('div', { ...rest, ref, 'data-native-component': componentNameClean }, children);
+  });
+  NativeComponent.displayName = componentName;
+
+  return NativeComponent;
+}
+
+module.exports = codegenNativeComponent;