Restructure world generation to trigger chunk loading based on player
movement. Replace player name with UUID for identification. Implement
chunk request/response protocol. Improve thread management for gen
thread.
Introduce packet header and ID mapping for protobuf messages.
Refactor session and server_world to use new packet wrapper.
Fix missing semicolons in proto files.
Add Protobuf dependency, define proto messages for player requests, positions, and chunk data. Refactor Session to use strand and async write. Implement player join/exit and position sync in ServerWorld.