Build a dinosaur runner game with Deno, pt. 5

Part 5 of a tutorial series on building a browser-based dinosaur runner game with Deno. This installment adds player identity and customization features: name prompts, theme selection (desert, forest, night, rainbow, space), difficulty settings, and color customization. The tutorial covers extending the HTML UI with modals, styling them with CSS, orchestrating settings in game.js, creating PostgreSQL tables for players and preferences, implementing Oak API routes for persistence, and validating the full loop. Players can now save their preferences, which persist across sessions and display on the global leaderboard.