initial: dungeon crawler with Bun + TypeScript modular architecture

- 19 TypeScript modules under src/ (constants, entities, room, game, render)
- Canvas 2D rendering with dark fantasy palette
- Room-based navigation, random 7x7 map generation
- Two combat modes: ranged (pistol) and melee (knife)
- Wall collision with door opening support
- Minimap, HP bar, enemy AI
- Bun build pipeline: src/main.ts -> dist/main.js + dist/index.html

.gitignore

@@ -0,0 +1,4 @@
+node_modules/
+dist/*.map
+*.log
+.DS_Store