feat: update E2E fixture settings and improve test repository initialization

- Changed the E2E settings to enable the use of worktrees for better test isolation.
- Modified the test repository initialization to explicitly set the initial branch to 'main', ensuring compatibility across different git versions and avoiding CI environment discrepancies.

apps/ui/scripts/setup-e2e-fixtures.mjs

@@ -46,7 +46,7 @@ const E2E_SETTINGS = {
   defaultSkipTests: true,
   enableDependencyBlocking: true,
   skipVerificationInAutoMode: false,
-  useWorktrees: false,
+  useWorktrees: true,
   showProfilesOnly: false,
   defaultPlanningMode: 'skip',
   defaultRequirePlanApproval: false,

apps/ui/tests/utils/git/worktree.ts

@@ -78,9 +78,6 @@ export async function createTestGitRepo(tempDir: string): Promise<TestRepo> {
   const tmpDir = path.join(tempDir, `test-repo-${Date.now()}`);
   fs.mkdirSync(tmpDir, { recursive: true });
 
-  // Initialize git repo
-  await execAsync('git init', { cwd: tmpDir });
-
   // Use environment variables instead of git config to avoid affecting user's git config
   // These env vars override git config without modifying it
   const gitEnv = {
@@ -91,13 +88,22 @@ export async function createTestGitRepo(tempDir: string): Promise<TestRepo> {
     GIT_COMMITTER_EMAIL: 'test@example.com',
   };
 
+  // Initialize git repo with explicit branch name to avoid CI environment differences
+  // Use -b main to set initial branch (git 2.28+), falling back to branch -M for older versions
+  try {
+    await execAsync('git init -b main', { cwd: tmpDir, env: gitEnv });
+  } catch {
+    // Fallback for older git versions that don't support -b flag
+    await execAsync('git init', { cwd: tmpDir, env: gitEnv });
+  }
+
   // Create initial commit
   fs.writeFileSync(path.join(tmpDir, 'README.md'), '# Test Project\n');
   await execAsync('git add .', { cwd: tmpDir, env: gitEnv });
   await execAsync('git commit -m "Initial commit"', { cwd: tmpDir, env: gitEnv });
 
-  // Create main branch explicitly
+  // Ensure branch is named 'main' (handles both new repos and older git versions)
-  await execAsync('git branch -M main', { cwd: tmpDir });
+  await execAsync('git branch -M main', { cwd: tmpDir, env: gitEnv });
 
   // Create .automaker directories
   const automakerDir = path.join(tmpDir, '.automaker');