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

src/input.ts

@@ -0,0 +1,18 @@
+// Global keyboard state (shared mutable map)
+export const KEYS: Record<string, boolean> = {};
+
+export function setupInput(): void {
+  window.addEventListener('keydown', (e: KeyboardEvent) => {
+    KEYS[e.key] = true;
+    if (['ArrowUp', 'ArrowDown', 'ArrowLeft', 'ArrowRight', ' '].includes(e.key)) {
+      e.preventDefault();
+    }
+  });
+  window.addEventListener('keyup', (e: KeyboardEvent) => {
+    KEYS[e.key] = false;
+  });
+  window.addEventListener('blur', () => {
+    // Reset all keys on window blur to avoid stuck keys
+    for (const k in KEYS) delete KEYS[k];
+  });
+}