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.

metro.config.js

@@ -19,6 +19,35 @@ config.resolver.alias = {
 // Ensure platform-specific files are resolved correctly
 config.resolver.platforms = ['ios', 'android', 'native', 'web'];
 
+// Web shims for native-only React Native APIs that don't exist in react-native-web.
+// Packages like react-native-pager-view import codegenNativeComponent from
+// react-native/Libraries/Utilities/codegenNativeComponent, which calls
+// requireNativeComponent internally. On web (react-native-web), these APIs
+// don't exist, causing "(0 , _reactNativeWebDistIndex.requireNativeComponent)
+// is not a function".
+const webShimPaths = [
+  'react-native/Libraries/Utilities/codegenNativeComponent',
+  'react-native/Libraries/Utilities/codegenNativeCommands',
+  'react-native/Libraries/Types/CodegenTypes',
+];
+
+const originalResolveRequest = config.resolver.resolveRequest;
+const shimDir = path.resolve(__dirname, 'web-shims');
+
+config.resolver.resolveRequest = (context, moduleName, platform) => {
+  if (platform === 'web' && webShimPaths.some((p) => moduleName.endsWith(p))) {
+    const shimName = moduleName.replace('react-native/Libraries/', '');
+    return {
+      type: 'sourceFile',
+      filePath: path.join(shimDir, 'react-native', 'Libraries', shimName + '.js'),
+    };
+  }
+  if (originalResolveRequest) {
+    return originalResolveRequest(context, moduleName, platform);
+  }
+  return context.resolveRequest(context, moduleName, platform);
+};
+
 // NOTE: enhanceMiddleware is marked as deprecated in Metro's types,
 // but there's currently no official alternative for custom dev server headers.
 // For production, configure COEP/COOP headers on your hosting platform.
@@ -31,4 +60,4 @@ config.server.enhanceMiddleware = (middleware) => {
   };
 };
 
-module.exports = config;
+module.exports = config;