Fine-Tuned & Visual Polish Update

[p]This update focuses on driving realism and visual enhancements:[/p]

• [p]Visual Upgrades: Replaced the police car model with a higher-detail version, improved headlight glow effects, and refined tutorial track barriers.[/p]
• [p]Fix: Rewritten torque and brake control code, fixing the random moving issue that sometimes occur after crossing the finish line.[/p]
• [p]AI Balancing: Adjusted AI opponent steering behavior for more natural and fair racing.[/p]