fix(game): resolve race condition in render dirty flag using bitwise OR

The render dirty flag was being reset instead of accumulated, causing
the game to become stuck and unplayable in web builds. Changed from
assignment to bitwise OR to preserve all dirty state updates.

Also adds game layout component and updates Justfile to build frontend.

web/pages/index/+Page.tsx

@@ -2,32 +2,27 @@ import { useEffect } from "react";
 
 export default function Page() {
   useEffect(() => {
-    // Only setup Module if not already configured (prevents double-initialization on hot reload)
     if (!(window as any).Module) {
       const canvas = document.getElementById("canvas");
 
-      // Simple Module configuration matching the original working approach
       (window as any).Module = {
         canvas: canvas,
         locateFile: (path: string) => {
-          // Return absolute paths for all resources
           return path.startsWith("/") ? path : `/${path}`;
         },
         preRun: [],
       };
 
-      // Load the Emscripten script
       const script = document.createElement("script");
       script.src = "/pacman.js";
-      script.async = false; // Load synchronously to ensure Module is configured first
+      script.async = false;
       document.body.appendChild(script);
 
-      // Cleanup function (runs when component unmounts)
       return () => {
         script.remove();
       };
     }
-  }, []); // Empty dependency array = run once on mount
+  }, []);
 
   return (
     <div className="mt-4 flex justify-center h-[calc(100vh-120px)]">