Add browser-based Doom clone with raycasting engine

Built a complete FPS game playable in the browser using vanilla JS and
HTML5 Canvas. Features a raycasting renderer with 8 textured wall types,
3 weapons (pistol, shotgun, plasma gun), 3 enemy types with AI
(imp, demon, baron), 3 levels of increasing difficulty, HUD with
minimap, pickups, doors, explosive barrels, and procedural audio.
Includes GitHub Actions workflow for GitHub Pages deployment.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

js/main.js

@@ -0,0 +1,10 @@
+// Entry point
+window.addEventListener('DOMContentLoaded', () => {
+    // Initialize procedural assets
+    initTextures();
+    initSprites();
+
+    // Create and start game
+    const game = new Game();
+    game.start();
+});