Merge upstream changes from main branch

This merge brings in new features and improvements from the main branch while
preserving Gitea-specific functionality:

- Updated README.md to maintain Gitea-specific setup instructions
- Preserved Gitea-specific authentication and API configurations
- Kept local git operations and MCP tool references for Gitea compatibility
- Removed GitHub-specific files (CONTRIBUTING.md, FAQ.md) and features
- Updated action.yml with new inputs while maintaining Gitea token usage
- Resolved conflicts in prompt generation to use Gitea comment tools

The merge maintains the Gitea fork's core functionality while incorporating
upstream bug fixes and feature enhancements.

examples/claude.yml

@@ -33,4 +33,16 @@ jobs:
         with:
           gitea_token: ${{ secrets.GITHUB_TOKEN }}
           anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
+          # Or use OAuth token instead:
+          # claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
           timeout_minutes: "60"
+          # mode: tag  # Default: responds to @claude mentions
+          # Optional: Restrict network access to specific domains only
+          # experimental_allowed_domains: |
+          #   .anthropic.com
+          #   .github.com
+          #   api.github.com
+          #   .githubusercontent.com
+          #   bun.sh
+          #   registry.npmjs.org
+          #   .blob.core.windows.net