GTAGPT Mobile Demo v2 Directional

Open mobile_demo_v2_directional.html on iPhone/Safari.

New in v2:
- Car rotates toward movement direction.
- Player rotates toward movement direction.
- Pedestrians rotate toward movement direction.
- 8-direction quantized rotation for retro top-down readability.
- Small yellow nose marker added to make facing direction readable even with placeholder sprites.

Controls:
- Left touch joystick: move / drive
- ENTER button: enter or exit car
- BOOST button: speed boost while driving
