feat: add GitHub repository provider

[flowerjunjie]

Adds GitHub API integration for repository management.

[vercel]

Someone is attempting to deploy a commit to the KeepHQ Team on Vercel.

A member of the Team first needs to authorize it.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

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