fix(canvas): ensure beginPath is called on circle polygon paths to prevent stray connecting lines

public/app.js

@@ -392,16 +392,17 @@
 
   // --- Helper: Polygon Path Generator ---
   function drawPolygonPath(targetCtx, sides, radius, cornerRadius = 0) {
+    targetCtx.beginPath();
     if (sides === 0) {
       // Circle
       targetCtx.arc(0, 0, radius, 0, Math.PI * 2);
+      targetCtx.closePath();
       return;
     }
 
     const angleStep = (Math.PI * 2) / sides;
     const startAngle = -Math.PI / 2; // Point top
 
-    targetCtx.beginPath();
     for (let i = 0; i < sides; i++) {
       const a = startAngle + i * angleStep;
       const x = Math.cos(a) * radius;