A12: Extract gamespy module #132

Summary

Extract GameSpy LAN discovery and master server heartbeat into a standalone module DLL.

Responsibility

• Respond to LAN browser queries (\status\ packets on ports 22101-22201)
• Build response with server info (hostname, map, numplayers, maxplayers, gamemode)
• Master server heartbeat (\heartbeat\ + challenge-response)
• Subscribe to: gamespy_query, player_joined, player_disconnected

Reference

• GameSpy Protocol

Acceptance Criteria

• LAN discovery works through module interface
• Master server heartbeat works
• Player count updates in real time

Depends on: #125 (protocol module)
Blocks: #120