feat: store local ID assigned by domain server for packet sourcing

src/OverteClient.hpp

@@ -96,6 +96,7 @@ private:
 	std::string m_sessionUUID; // Our client session UUID
 	std::string m_username;     // Domain account username (for future signature-based auth)
 	std::uint32_t m_sequenceNumber{0};  // Packet sequence number for NLPacket protocol
+	std::uint16_t m_localID{0};         // Local ID assigned by domain server
 
 	// Very small in-process world state for testing
 	std::unordered_map<std::uint64_t, OverteEntity> m_entities;