fix(map): add world plane collision and respawn

src/world/collision/WorldPlaneCollision.tsx

@@ -0,0 +1,20 @@
+import { WORLD_BOUNDS_CONFIG } from "@/data/world/worldBoundsConfig";
+
+export function WorldPlaneCollision(): React.JSX.Element | null {
+  if (!WORLD_BOUNDS_CONFIG.enabled) {
+    return null;
+  }
+
+  const { center, planeCollisionThickness, planeY, size } = WORLD_BOUNDS_CONFIG;
+  const [width, depth] = size;
+
+  return (
+    <mesh
+      name="world-plane-collision"
+      position={[center[0], planeY - planeCollisionThickness / 2, center[2]]}
+    >
+      <boxGeometry args={[width, planeCollisionThickness, depth]} />
+      <meshBasicMaterial />
+    </mesh>
+  );
+}