fix: recover worktree bootstrap from stale index.lock

Retries transient index.lock conflicts during worktree population
Removes unchanged stale locks automatically and continues bootstrap
Adds coverage for stale lock recovery

packages/web/server/lib/git/service.test.js

@@ -10,6 +10,7 @@ import {
   cherryPick,
   createWorktree,
   getStatus,
+  populateWorktreeWithLockRecovery,
   removeWorktree,
   resolvePrimaryWorktreeRoot,
   resolveWorktreeTopLevel,
@@ -321,6 +322,28 @@ describe('worktree root resolution', () => {
 // ---------------------------------------------------------------------------
 
 describe('createWorktree', () => {
+  it('recovers from an unchanged stale index lock while populating a worktree', async () => {
+    if (!canRunGit()) return;
+
+    const repo = createTempDir();
+    const worktree = createTempDir();
+    runGit(repo, ['init', '-b', 'main']);
+    runGit(repo, ['config', 'user.email', 'test@example.com']);
+    runGit(repo, ['config', 'user.name', 'Test User']);
+    fs.writeFileSync(path.join(repo, 'README.md'), '# Test\n');
+    runGit(repo, ['add', 'README.md']);
+    runGit(repo, ['commit', '-m', 'Initial commit']);
+    fs.rmSync(worktree, { recursive: true, force: true });
+    runGit(repo, ['worktree', 'add', '--no-checkout', '-b', 'feature/stale-lock', worktree, 'HEAD']);
+
+    const lockPath = runGit(worktree, ['rev-parse', '--git-path', 'index.lock']).trim();
+    fs.writeFileSync(lockPath, 'stale');
+
+    await expect(populateWorktreeWithLockRecovery(worktree)).resolves.toBeUndefined();
+    expect(fs.existsSync(lockPath)).toBe(false);
+    expect(fs.readFileSync(path.join(worktree, 'README.md'), 'utf8')).toBe('# Test\n');
+  });
+
   it('preflights fast create branch-in-use failures before creating the candidate directory', async () => {
     if (!canRunGit()) return;