Add -c/--clone option to clone repository.

[saimizi]

What's changed

Add -c/--clone option to clone the repository.

Example

# Clone repository to default directory (repository name)
ghr -c owner/repo

# Clone to specific directory
ghr -c owner/repo my-directory

# Clone specific branch
ghr -c owner/repo:main my-directory

# Clone specific tag
ghr -c owner/repo:v1.0.0 my-directory

# Clone specific commit
ghr -c owner/repo:abc1234 my-directory

# Clone with HTTPS URL
ghr -c https://github.com/owner/repo

# Clone private repository (requires authentication)
ghr -t YOUR_TOKEN -c owner/private-repo my-directory