Initial commit: Western Shooter - Complete implementation

Retro western vertical shooter inspired by Gun.Smoke, built with
TypeScript and WebGL2. Features 3-direction shooting, vertical
scrolling, economy/shop loop, boss fights, and CRT shader effects.

Phases implemented:
- Phase 1: Engine skeleton (WebGL2 renderer, fixed timestep loop, input)
- Phase 2: Shooting identity (3-dir shooting, bullet pools, collision)
- Phase 3: Enemies & patterns (JSON waves, 4 enemy types, parallax bg)
- Phase 4: Economy loop (pickups, shop, upgrades, HUD)
- Phase 5: Boss system (3 bosses, wanted posters, multi-phase attacks)
- Phase 6: Shader layer (CRT effects, bloom, scanlines, screen shake)
- Phase 7: Performance (VAO batching, O(1) allocation, stress testing)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

index.html

@@ -0,0 +1,35 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0">
+  <title>Western Shooter</title>
+  <style>
+    * {
+      margin: 0;
+      padding: 0;
+      box-sizing: border-box;
+    }
+    html, body {
+      width: 100%;
+      height: 100%;
+      background: #000;
+      overflow: hidden;
+    }
+    #game-canvas {
+      display: block;
+      margin: auto;
+      position: absolute;
+      top: 50%;
+      left: 50%;
+      transform: translate(-50%, -50%);
+      image-rendering: pixelated;
+      image-rendering: crisp-edges;
+    }
+  </style>
+</head>
+<body>
+  <canvas id="game-canvas"></canvas>
+  <script type="module" src="./src/main.ts"></script>
+</body>
+</html>