Setup automatic mirroring to GitLab and Bitbucket

[konard]

🎯 Summary

This PR implements automatic repository mirroring to GitLab and Bitbucket as requested in issue #82. The solution provides:

• Automatic mirroring of all branches and tags to both platforms
• Safe branch deletion that only replicates deletions if branches were fully merged
• Complete backup solution maintaining full repository history
• Multi-platform accessibility making the project easily accessible from multiple places

📋 Issue Reference

Fixes #82

🚀 Implementation Details

Core Features

1. Comprehensive Mirroring Workflow (.github/workflows/mirror-repositories.yml)

   • Mirrors all push events to both GitLab and Bitbucket
   • Handles branch and tag synchronization
   • Implements safe branch deletion with merge verification
   • Includes error handling and fallback mechanisms

2. Setup Documentation (MIRRORING_SETUP.md)

   • Complete configuration guide
   • Security considerations and best practices
   • Troubleshooting instructions
   • Manual sync procedures for emergencies

Safety Features

• Merge Verification: Branch deletions only replicated if fully merged into main branch
• Error Handling: Graceful fallbacks if mirror operations fail
• Secure Authentication: Uses encrypted GitHub secrets for credentials
• Isolation: Separate jobs for each platform prevent cross-contamination

Workflow Triggers

• push: Mirrors all branch and tag pushes
• delete: Handles branch deletions with merge safety checks
• Separate job for tag mirroring with dedicated handling

🔧 Setup Requirements

The following GitHub secrets need to be configured:

GitLab

• GITLAB_TOKEN: Personal Access Token with api, read_repository, write_repository scopes
• GITLAB_PROJECT_PATH: Target project path (e.g., linksplatform/interfaces)

Bitbucket

• BITBUCKET_USERNAME: Your Bitbucket username
• BITBUCKET_APP_PASSWORD: App password with Repositories: Write permission
• BITBUCKET_PROJECT_PATH: Target repository path (e.g., linksplatform/interfaces)

🧪 Testing

• ✅ YAML syntax validation passed
• ✅ Workflow structure verified
• ✅ Error handling paths tested
• ✅ Security review completed
• ✅ Documentation comprehensiveness checked

📚 Files Changed

• .github/workflows/mirror-repositories.yml - Main mirroring workflow
• MIRRORING_SETUP.md - Comprehensive setup and usage documentation

🔒 Security Considerations

• All credentials stored as encrypted GitHub secrets
• HTTPS-only authentication
• Minimal permission requirements
• No secret exposure in logs
• Safe branch deletion prevents accidental data loss

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This solution provides a robust, secure, and maintainable mirroring system that meets all requirements specified in issue #82.