Add minimal 3D track rendering prototype

[Hartwich]

Goal

Add a minimal 3D rendering prototype for Drift Racer.

Codex Auftrag

Keep existing game logic as much as possible while adding a basic 3D host view.

Focus

• simple 3D track plane or road
• simple placeholder vehicle mesh
• camera that follows the race clearly
• keep existing game logic as much as possible

Acceptance Criteria

• Game can still be launched through Open Party Lab.
• Host shows a basic 3D scene.
• Placeholder visuals are acceptable.
• Existing controller flow still works or limitations are documented.
• npm run typecheck passes.
• npm run build passes.

Safety

Do not add copyrighted, unclear, or unreviewed third-party assets or content.