Work on private repositories

If the repository is private then freepilot-bot would have to be manually added as a collaborator with "Write" access.

There would need to be a clear error for this when you paste an issue link for a private repository and freepilot-bot does not have access. There should be instructions to add freepilot-bot as a collaborator (link to https://github.com/organization/repo/settings/access to add exactly `freepilot-bot` as a collaborator with write access, and then try the job again) There should also be a link to README to learn more about using freepilot with private repositories.

For jobs, the repository should be checked if it is private or not. Instead of forking and syncing the forked repository, it should just clone the main repository. Once the agent changes are made, the changes should be pushed to the original repository and PRs made directly from the branch instead of a branch on the forked repository.

Update the README with a section for private repositories and the implications that freepilot has access to your code, and that freepilot should not take any responsibility for any possible damage in any form. You can self-host freepilot if you have any concerns.