Fix gravity reset and add spawn cap for swirl arena

src/ui.js

@@ -148,7 +148,8 @@
       if (!point || !sceneEl) return;
       const el = document.createElement("div");
       el.className = "floating-score";
-      el.textContent = `+${amount}`;
+      const sign = amount > 0 ? "+" : "";
+      el.textContent = `${sign}${amount}`;
       el.style.left = `${point.x}px`;
       el.style.top = `${point.y}px`;
       el.style.color = color || "#e0f2fe";