Add stack blocks scene with column spawning

src/scenes/scene-stack-blocks.js

@@ -0,0 +1,71 @@
+(() => {
+  const { Bodies } = Matter;
+  const scenes = (window.PhysilinksSceneDefs =
+    window.PhysilinksSceneDefs || []);
+
+  scenes.push({
+    id: "stack-blocks",
+    name: "Stack Blocks",
+    config: {
+      gravity: 1.05,
+      spawnIntervalMs: 900,
+      autoSpawn: true,
+      minChain: 3,
+      palette: ["#38bdf8", "#f97316", "#facc15", "#22c55e"],
+      ballRadius: 18,
+      ballShape: "rect",
+      spawnColumns: 10,
+      initialRows: 3,
+      winCondition: {
+        type: "clearCount",
+        target: 100,
+      },
+      link: {
+        stiffness: 0.85,
+        lengthScale: 1.05,
+        damping: 0.08,
+        lineWidth: 3,
+        rope: true,
+        renderType: "line",
+        maxLengthMultiplier: 3.1,
+      },
+    },
+    createBodies: (w, h) => {
+      const wallThickness = Math.max(20, w * 0.02);
+      const floorHeight = Math.max(30, h * 0.06);
+      return [
+        Bodies.rectangle(
+          -wallThickness / 2,
+          h / 2,
+          wallThickness,
+          h * 2,
+          {
+            isStatic: true,
+            render: { fillStyle: "#0b1222", strokeStyle: "#0b1222" },
+          },
+        ),
+        Bodies.rectangle(
+          w + wallThickness / 2,
+          h / 2,
+          wallThickness,
+          h * 2,
+          {
+            isStatic: true,
+            render: { fillStyle: "#0b1222", strokeStyle: "#0b1222" },
+          },
+        ),
+        Bodies.rectangle(
+          w / 2,
+          h + floorHeight / 2,
+          w + wallThickness * 2,
+          floorHeight,
+          {
+            isStatic: true,
+            restitution: 0.2,
+            render: { fillStyle: "#0b1222", strokeStyle: "#0b1222" },
+          },
+        ),
+      ];
+    },
+  });
+})();