Fix metro config to always add monorepo root to watchFolders

The previous condition only added watchFolders if the array was empty,
but @rnx-kit/metro-config might return a non-empty array. This caused
the macOS test app to fail to resolve @React-Native-Node-API packages
during bundling.

Fixes the UnableToResolveError for @react-native-node-api/node-addon-examples

Co-authored-by: Kræn Hansen <mail@kraenhansen.dk>

Author: cursoragent

apps/test-app/metro.config.js

@@ -11,12 +11,16 @@ const config = makeMetroConfig({
   },
 });
 
-if (config.watchFolders.length === 0) {
-  // This patch is needed to locate packages in the monorepo from the MacOS app
-  // which is intentionally kept outside of the workspaces configuration to prevent
-  // duplicate react-native version and pollution of the package lock.
-  const path = require("node:path");
-  config.watchFolders.push(path.resolve(__dirname, "../.."));
+// This patch is needed to locate packages in the monorepo from the MacOS app
+// which is intentionally kept outside of the workspaces configuration to prevent
+// duplicate react-native version and pollution of the package lock.
+const path = require("node:path");
+const monorepoRoot = path.resolve(__dirname, "../..");
+if (!config.watchFolders) {
+  config.watchFolders = [];
+}
+if (!config.watchFolders.includes(monorepoRoot)) {
+  config.watchFolders.push(monorepoRoot);
 }
 
 module.exports = config;