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>

data/stage1.json

@@ -0,0 +1,65 @@
+{
+  "id": "stage1",
+  "name": "Dusty Trail",
+  "scrollSpeed": 20,
+  "waves": [
+    {
+      "id": "wave1",
+      "duration": 5,
+      "spawns": [
+        { "type": "bandit", "x": "center", "delay": 0 },
+        { "type": "bandit", "x": "left", "delay": 0.5 },
+        { "type": "bandit", "x": "right", "delay": 0.5 }
+      ]
+    },
+    {
+      "id": "wave2",
+      "duration": 6,
+      "spawns": [
+        { "type": "gunman", "x": "left", "delay": 0 },
+        { "type": "gunman", "x": "right", "delay": 0 },
+        { "type": "bandit", "x": "center", "delay": 1 },
+        { "type": "bandit", "x": "random", "delay": 2 },
+        { "type": "bandit", "x": "random", "delay": 2.5 }
+      ]
+    },
+    {
+      "id": "wave3",
+      "duration": 7,
+      "spawns": [
+        { "type": "rifleman", "x": "center", "delay": 0 },
+        { "type": "bandit", "x": "left", "delay": 0.5 },
+        { "type": "bandit", "x": "right", "delay": 0.5 },
+        { "type": "gunman", "x": "random", "delay": 2 },
+        { "type": "gunman", "x": "random", "delay": 3 }
+      ]
+    },
+    {
+      "id": "wave4",
+      "duration": 8,
+      "spawns": [
+        { "type": "dynamite", "x": "center", "delay": 0 },
+        { "type": "bandit", "x": "left", "delay": 0 },
+        { "type": "bandit", "x": "right", "delay": 0 },
+        { "type": "rifleman", "x": "left", "delay": 2 },
+        { "type": "rifleman", "x": "right", "delay": 2 },
+        { "type": "gunman", "x": "center", "delay": 4 }
+      ]
+    },
+    {
+      "id": "wave5",
+      "duration": 10,
+      "spawns": [
+        { "type": "gunman", "x": "left", "delay": 0 },
+        { "type": "gunman", "x": "right", "delay": 0 },
+        { "type": "gunman", "x": "center", "delay": 0 },
+        { "type": "rifleman", "x": "random", "delay": 2 },
+        { "type": "rifleman", "x": "random", "delay": 2.5 },
+        { "type": "dynamite", "x": "random", "delay": 4 },
+        { "type": "bandit", "x": "random", "delay": 5 },
+        { "type": "bandit", "x": "random", "delay": 5.5 },
+        { "type": "bandit", "x": "random", "delay": 6 }
+      ]
+    }
+  ]
+}