Introduce GUI test tooling that spawns synthetic TCP clients for local relay testing. Adds server/fake_player.py implementing FakePlayerClient and FakePlayerManager which create TCP connections to 127.0.0.1:7777, parse newline-delimited JSON, receive server-assigned playerId, and send one idle transform per second for cell 0B000F99. Integrates the manager into server/dev_server_app.py: start/stop lifecycle handling, Add/Remove buttons, table snapshots, logging bridge, and clean shutdown of fake clients. Updates server/README.md and docs/dev-log.md with usage, testing notes, and known issues. Includes basic error handling and thread-safe snapshots; movement scripts beyond Idle and full in-game validation are noted as next steps.