Implement backup and recovery system

[Josue19-08]

💾 Implement backup and recovery system

Fixes #173

📋 Description

Implements a comprehensive backup and recovery system for critical contract data in both user_management and course_registry contracts. This system allows administrators to export and import all essential data for disaster recovery and system migration purposes.

🔧 Changes Made

User Management Contract

• ✅ Added export_user_data() function - Exports all user profiles, admin configuration, and system metadata
• ✅ Added import_user_data() function - Imports user data with version validation and integrity checks
• ✅ Created UserBackupData struct with comprehensive data structure including timestamps and versioning
• ✅ Implemented admin-only access control for all backup operations

Course Registry Contract

• ✅ Added export_course_data() function - Exports courses, categories, modules, goals, and prerequisites
• ✅ Added import_course_data() function - Restores complete course data with validation
• ✅ Created CourseBackupData struct with full course ecosystem backup support
• ✅ Implemented proper iteration through course storage mechanism

🛡️ Security Features

• Admin-only operations - Only administrators can perform backup/recovery
• Authentication required - All operations require caller authentication
• Version validation - Backup compatibility checking (v1.0.0)
• Integrity verification - Data validation during import/export
• Audit events - System events for tracking backup operations

🧪 Testing

• ✅ Comprehensive test coverage for both contracts
• ✅ Admin permission validation tests
• ✅ Data integrity verification tests
• ✅ Import/export functionality tests
• ✅ All tests passing without warnings

📁 Files Changed

contracts/user_management/src/
├── lib.rs (new public functions)
├── schema.rs (UserBackupData struct)
├── functions/
│   ├── backup_recovery.rs (new implementation)
│   └── mod.rs (new module)
└── test.rs (backup tests)

contracts/course/course_registry/src/
├── lib.rs (new public functions)
├── schema.rs (CourseBackupData struct)
├── functions/
│   ├── backup_recovery.rs (new implementation)
│   └── mod.rs (updated module)
└── test.rs (backup tests)

🚀 Usage Example

// Export user data (admin only)
let backup_data = client.export_user_data(&admin_address);

// Import user data (admin only)
let imported_count = client.import_user_data(&admin_address, &backup_data);

// Export course data (admin only)
let course_backup = client.export_course_data(&admin_address);

// Import course data (admin only)
let courses_imported = client.import_course_data(&admin_address, &course_backup);

✅ Checklist

• Functions implemented in both contracts
• Admin-only access control
• Version compatibility system
• Comprehensive test coverage
• Documentation in English
• No compilation errors
• All tests passing
• Follows Soroban best practices

📊 Priority: Low ✅ COMPLETED

This implementation provides a robust backup and recovery system that ensures data preservation and system reliability for the SkillCert platform.

---

Ready for review and merge! 🎉