1.0.0: Add unit tests and fuzz tests for RakNet core functionality

- Introduced `test_core.cpp` with standalone unit tests for BinaryStream, EncapsulatedPacket, AcknowledgePacket, and more.
- Added `test_fuzz.cpp` for deterministic fuzz testing of decoding paths to ensure no crashes or undefined behavior.
- Created `encapsulated_roundtrip.phpt` to validate byte-exact roundtrip for EncapsulatedPacket using reference vectors from the PHP implementation.
- Implemented `server_lifecycle.phpt` to test native server lifecycle including binding, offline ping/pong, blocking/unblocking addresses, and shutdown.
- Added `shared_types.phpt` to verify shared types such as constants, exceptions, interfaces, and value classes.
- Included `version_constant.phpt` to ensure the RakLib extension loads and registers its version constant.