Remove Hello World Example

[SorraTheOrc]

Summary

Replace the Hello World example with Gym scenes so the repository has a single curated demo surface aligned to current engine capabilities.

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

• example-games/hello-world/ is removed from the repository.
• No selector or docs references remain for Hello World as an active example.
• Equivalent baseline smoke coverage is present through Gym scenes.
• npm test and npm run build pass after removal.
• Migration notes explain where former Hello World use-cases now live.

Minimal Implementation

• Remove Hello World files and selector registration.
• Migrate any required smoke assertions to Gym coverage.
• Update docs and references to point to Gym scenes.
• Run full test/build quality gates and capture results.
• Document migration mapping from Hello World to Gym.

Dependencies

• Gym Shell & Router
• Deck & Seeded RNG Demos
• Headless Smoke for All Scenes
• Gym Documentation Pack

Deliverables

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

[SorraTheOrc]

Map

Batch intake run completed.

Parent: CG-0MP3XQBL4008QK8S
Validation checks: {"has_summary": true, "has_acceptance": true, "has_min_impl": true, "has_dependencies": true, "has_deliverables": true}
Result: work item is sufficiently defined for planning/implementation tracking.