Support for Additional Git Forges (e.g., Codeberg) in Codex

What feature would you like to see?

Summary
Codex currently integrates only with GitHub. It would be valuable to extend support to other Git forges, particularly Codeberg, as well as other platforms compatible with the Gitea API.

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Motivation / Use Case
Many developers and organizations host code on alternative platforms for reasons including:
• Commitment to open-source and federated infrastructure
• Privacy and data-sovereignty concerns
• Desire to avoid reliance on a single proprietary service

Supporting Codeberg and other Gitea-based instances would allow a much broader community to use Codex for repository exploration, analysis, and automation.

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Proposed Solution
• Add authentication and repository access support for non-GitHub forges.
• Implement a modular integration layer so Codex can interface with Gitea-compatible APIs.
• Allow users to configure multiple forges (e.g., GitHub + Codeberg) via settings or environment variables.
• Reuse existing Git operations (clone, fetch, read files) regardless of the forge source.

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Benefits
• Expands Codex’s reach to open-source-first communities.
• Aligns with open standards and decentralization efforts.
• Encourages adoption in research, education, and self-hosted environments.
• Future-proofs Codex against single-provider dependencies.

Additional information

_No response_