feat(03-01): add createTempGitProject helper to tests/helpers.cjs

- Creates temp dir with .planning/phases structure
- Initializes git repo with user config
- Writes initial PROJECT.md and commits it
- Exports createTempGitProject alongside existing helpers

tests/helpers.cjs

@@ -33,8 +33,28 @@ function createTempProject() {
   return tmpDir;
 }
 
+// Create temp directory with initialized git repo and at least one commit
+function createTempGitProject() {
+  const tmpDir = fs.mkdtempSync(path.join(require('os').tmpdir(), 'gsd-test-'));
+  fs.mkdirSync(path.join(tmpDir, '.planning', 'phases'), { recursive: true });
+
+  execSync('git init', { cwd: tmpDir, stdio: 'pipe' });
+  execSync('git config user.email "test@test.com"', { cwd: tmpDir, stdio: 'pipe' });
+  execSync('git config user.name "Test"', { cwd: tmpDir, stdio: 'pipe' });
+
+  fs.writeFileSync(
+    path.join(tmpDir, '.planning', 'PROJECT.md'),
+    '# Project\n\nTest project.\n'
+  );
+
+  execSync('git add -A', { cwd: tmpDir, stdio: 'pipe' });
+  execSync('git commit -m "initial commit"', { cwd: tmpDir, stdio: 'pipe' });
+
+  return tmpDir;
+}
+
 function cleanup(tmpDir) {
   fs.rmSync(tmpDir, { recursive: true, force: true });
 }
 
-module.exports = { runGsdTools, createTempProject, cleanup, TOOLS_PATH };
+module.exports = { runGsdTools, createTempProject, createTempGitProject, cleanup, TOOLS_PATH };