Support analyzing repositories from a GitHub URL

[Syqens]

Summary

Add support for passing a GitHub repository URL, not just a local path.

Why

Right now the tool is strongest when the repository is already cloned locally. For a portfolio tool aimed at evaluating open-source contribution targets, it would be more useful if users could paste a GitHub URL directly.

Proposed behavior

• accept inputs like https://github.com/owner/repo
• clone the repository into a temporary working directory or a cache directory
• run the existing analysis flow on the cloned repository
• clean up temporary files after the report is generated

Notes

• keep the current local-path workflow unchanged
• make the remote workflow optional and clearly separated from the local one
• handle invalid URLs and clone failures with clear error messages