- Remove 'using namespace ipc::shm;' to avoid id_t conflict with system id_t
- Add explicit shm:: namespace prefix to all shm types and functions
- Apply to: id_t, handle, acquire, get_mem, release, remove, get_ref, sub_ref
- Apply to: create and open constants
- Fix comments to avoid incorrect namespace references
- Resolves compilation error: 'reference to id_t is ambiguous'
- Test low-level API (acquire, get_mem, release, remove)
- Test reference counting functionality (get_ref, sub_ref)
- Test high-level handle class interface
- Test all handle methods (valid, size, name, get, etc.)
- Test handle lifecycle (construction, move, swap, assignment)
- Test different access modes (create, open, create|open)
- Test detach/attach functionality
- Test multi-handle access to same memory
- Test data persistence across handles
- Test edge cases (large segments, multiple simultaneous handles)
- Move all existing test files (*.cpp, *.h) to test/archive/
- Rename CMakeLists.txt to CMakeLists.txt.old in archive
- Prepare for comprehensive unit test refactoring
