[codex] Implement Epic 10 canvas renderer

[PilHliP211]

Summary

Implements Epic 10's canvas renderer foundation for Phase 3 flag restoration.

• Adds a DPR-scaled CanvasRenderer with an accessible reset control and imperative canvas handle.
• Adds the renderer API, scoped function whitelist, call logging, sequential animation, and semantic success evaluator.
• Adds a temporary /__dev/canvas harness backed by a Flag Hunter dev fixture so the Japan restore flow can be exercised before LessonScreen lands in E-11.
• Adds unit and component coverage for renderer calls, whitelist boundaries, animation cancellation, success evaluation, canvas reset, and route wiring.

Validation

• npm run lint
• npx tsc --noEmit
• npm run test
• npm run format:check
• npm run build

npm run build still reports the existing Vite Monaco large-chunk warning, but completed successfully.