Gym Documentation Pack #782

Summary

Deliver comprehensive Gym documentation so developers can run, test, and extend scenes with minimal onboarding friction.

Player/User Experience Change

• Player-facing: this feature introduces a clear, interactive Gym slice demonstrating the capability in a runnable scene.
• Developer-facing: this feature provides deterministic tests and usage docs for repeatable validation.

Acceptance Criteria

• Every Gym scene has a short README/usage snippet.
• A centralized Gym index links all scenes and run/test commands.
• In-code comments cover public API touchpoints used by Gym.
• Developer docs explain how to add a new Gym scene end to end.
• Documentation is updated to remove stale Hello World guidance.

Minimal Implementation

• Create example-games/gym/README.md and per-scene usage snippets.
• Add centralized Gym index in docs/ and link from README.
• Update docs/DEVELOPER.md with Gym workflows and extension steps.
• Refresh in-code comments for public APIs exercised by Gym scenes.
• Cross-link headless smoke instructions and scene matrix.

Dependencies

• Gym Shell & Router
• Deck & Seeded RNG Demos
• Hand/Pile Interaction Demos
• Overlay & UI Config Demos
• Undo/Redo Workflow Demo
• Transcript Recording Demo
• Save/Load State Demo
• Audio & Feedback Config Demo
• Headless Smoke for All Scenes

Deliverables

• Code changes for the Gym scene slice
• Automated tests (unit/browser/headless as appropriate)
• Documentation updates (scene snippet + centralized index linkage)