feat: add Firebase Performance SDK integration script

starter/scripts/firebase_performance.dart

@@ -0,0 +1,77 @@
+import 'dart:io';
+
+import 'utils.dart';
+import 'utils/firebase_utils.dart';
+
+// Adds the Firebase Performance SDK to the project
+void main(List<String> arguments) {
+  List<String> platforms = getPlatforms(arguments);
+
+  try {
+    addDependency('firebase_performance', '^0.10.0+11');
+
+    if (platforms.contains('android')) {
+      addClasspathDependency(
+          "classpath 'com.google.firebase:perf-plugin:1.4.2'");
+      addPluginDependency("apply plugin: 'com.google.firebase.firebase-perf'");
+    }
+
+    // Configure iOS-specific settings
+    if (platforms.contains('ios')) {
+      addPod('FirebasePerformance');
+    }
+
+    print(
+        'Firebase Performance SDK enabled successfully for ${platforms.join(', ')}! 🎉');
+    exit(0);
+  } catch (e) {
+    print('Starter Error: $e');
+    exit(1);
+  }
+}
+
+void addPod(String pod) {
+  final podfile = File('ios/Podfile');
+  if (!podfile.existsSync()) {
+    throw 'ios/Podfile not found';
+  }
+
+  final lines = podfile.readAsLinesSync();
+  final newLines = <String>[];
+  bool added = false;
+
+  for (var line in lines) {
+    newLines.add(line);
+    if (line.contains('use_frameworks!')) {
+      newLines.add("  pod '$pod'");
+      added = true;
+    }
+  }
+
+  if (!added) {
+    throw 'use_frameworks! not found in ios/Podfile';
+  }
+
+  podfile.writeAsStringSync(newLines.join('\n'));
+}
+
+void addDependency(String dependency, String version) {
+  final pubspec = File('pubspec.yaml');
+  if (!pubspec.existsSync()) {
+    throw 'pubspec.yaml not found';
+  }
+
+  // find dependencies section with regex, don't do it with lines
+  final content = pubspec.readAsStringSync();
+  final dependencies =
+      RegExp(r'dependencies:', multiLine: true).firstMatch(content);
+
+  if (dependencies == null) {
+    throw 'dependencies section not found in pubspec.yaml';
+  }
+
+  final newContent = content.replaceFirst(dependencies.group(0)!,
+      '${dependencies.group(0)}\n  $dependency: $version\n');
+
+  pubspec.writeAsStringSync(newContent);
+}