Updated all route handlers to use await for async git helper functions:
- GET /git/remotes
- GET /git/remotes/detailed
- GET /git/status
- GET /git/commits
- GET /git/commits/:hash/diff
- GET /git/commits/ahead
- GET /git/branches
- GET /git/branches/:name/commits
- GET /git/worktrees
- GET /git/stashes
- POST /git/remotes
- DELETE /git/remotes/:name
- PATCH /git/remotes/:name
- PUT /git/remotes/:name/url
- GET /git/remotes/:name/commits
- POST /git/branches
- POST /git/branches/:name/checkout
- DELETE /git/branches/:name
- POST /git/fetch
- POST /git/pull
- POST /git/push
- POST /git/stashes
- POST /git/stashes/:index/apply
- DELETE /git/stashes/:index
- GET /git/diff
- GET /git/changes