Phase 7: OpenEnv server (ShutdownGymEnvironment, create_app wiring, EnvClient), custom-action mode, turn-budget timer per PROJECT.md Sections 4, 8, 10, 11, 13

Fix OpenEnv package: swap squatter openenv for openenv-core>=0.2.1, update PROJECT.md API sections and rubrics imports to match real Meta-PyTorch framework

Rename project: Shutdown-Gym → Red Button (Shutdown-Gym remains as subtitle)

Phase 1: Initial scaffold, Claude Code workspace, repo structure per PROJECT.md Section 5