Improve Page struct #11
Description
- Add uniquely identifies a page in the database
- Add Page manger to handle the lifecycle of pages
- Add serialization support
- Add PageAllocator that manages free pages and allocates new ones
- Add PageBuffer that manages cached pages in memory
- Add RecordPage that specifically handles storing records
- Block navigation methods (NextBlock, PrevBlock, IsFirst)
- Deep copy functionality
- Comprehensive test suite
- Performance benchmarks
- Input validation
- Additional helper methods