CI fixes (#2825)

Configure CI to skip samples that only fail in beta

tool/clean_all.dart

@@ -0,0 +1,76 @@
+import 'dart:io';
+import 'package:path/path.dart' as path;
+import 'package:yaml/yaml.dart';
+
+/// Runs `flutter clean` in every package listed in the root pubspec.yaml
+/// workspace. Useful for clearing stale build artifacts after switching Flutter
+/// channels.
+Future<void> main() async {
+  final rootDir = Directory.current;
+  final pubspecFile = File(path.join(rootDir.path, 'pubspec.yaml'));
+  final pubspecContent = await pubspecFile.readAsString();
+  final pubspecYaml = loadYaml(pubspecContent);
+
+  final workspace = pubspecYaml['workspace'] as YamlList?;
+  if (workspace == null) {
+    print('No workspace found in pubspec.yaml');
+    exit(1);
+  }
+
+  final flutterBin = _resolveFlutterBin();
+  print('Using flutter: $flutterBin');
+
+  var cleaned = 0;
+  var skipped = 0;
+
+  for (final entry in workspace) {
+    final package = entry.toString();
+    final packagePath = path.join(rootDir.path, package);
+
+    // Only clean packages that have a pubspec.yaml (i.e. are Flutter/Dart pkgs)
+    final pubspec = File(path.join(packagePath, 'pubspec.yaml'));
+    if (!await pubspec.exists()) {
+      print('-- Skipping \'$package\' (no pubspec.yaml found)');
+      skipped++;
+      continue;
+    }
+
+    print('== Cleaning \'$package\' ==');
+    final process = await Process.start(
+      flutterBin,
+      ['clean'],
+      workingDirectory: packagePath,
+      runInShell: true,
+      mode: ProcessStartMode.inheritStdio,
+    );
+    final exitCode = await process.exitCode;
+    if (exitCode != 0) {
+      print(
+        'Warning: flutter clean failed with exit code $exitCode in $packagePath',
+      );
+    } else {
+      cleaned++;
+    }
+  }
+
+  print('');
+  print('Done. Cleaned $cleaned package(s), skipped $skipped.');
+}
+
+/// Resolves the path to the `flutter` binary by finding it relative to the
+/// running Dart SDK. Falls back to 'flutter' (uses PATH) if not found.
+String _resolveFlutterBin() {
+  // Platform.resolvedExecutable points to the dart binary, e.g.:
+  //   /path/to/flutter/bin/cache/dart-sdk/bin/dart
+  // Flutter binary is at /path/to/flutter/bin/flutter
+  final dartBin = File(Platform.resolvedExecutable);
+  final flutterBin = path.join(
+    dartBin.parent.parent.parent.parent.path,
+    'bin',
+    'flutter',
+  );
+  if (File(flutterBin).existsSync()) {
+    return flutterBin;
+  }
+  return 'flutter'; // fallback to PATH
+}