Add plugin repositories to Android settings.gradle for resilient dependency resolution

The Gradle foojay-resolver-convention plugin needs gson from Maven Central,
which intermittently returns 403. Adding explicit pluginManagement repositories
(gradlePluginPortal, google, mavenCentral) provides fallback mirrors.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: kieran-osgood-shopify

sample/android/settings.gradle

@@ -1,4 +1,11 @@
-pluginManagement { includeBuild("../../node_modules/@react-native/gradle-plugin") }
+pluginManagement {
+    repositories {
+        gradlePluginPortal()
+        google()
+        mavenCentral()
+    }
+    includeBuild("../../node_modules/@react-native/gradle-plugin")
+}
 plugins { id("com.facebook.react.settings") }
 extensions.configure(com.facebook.react.ReactSettingsExtension){ ex -> ex.autolinkLibrariesFromCommand() }