[CircularProgressIndicator] Fix full circle track seam artifact

When drawing a full circle (360°) track, drawArc() creates a visible
seam at 0° where the start/end caps or rounded blocks overlap.

Replace drawArc() with drawOval() for full circle tracks, which has
no start/end point and renders a seamless circle.

Partial arcs (indicators) continue to use drawArc() unchanged.

Fixes #5027

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Nanamare

lib/java/com/google/android/material/progressindicator/CircularDrawingDelegate.java

@@ -313,6 +313,18 @@ private void drawArc(
             && shouldDrawActiveIndicator
             && amplitudeFraction > 0f;
 
+    // Full circle: use drawOval to avoid seam artifact at the start/end point where caps overlap.
+    if (arcDegree >= 360f && !shouldDrawWavyPath) {
+      paint.setAntiAlias(true);
+      paint.setColor(paintColor);
+      paint.setStrokeWidth(displayedTrackThickness);
+      paint.setStyle(Style.STROKE);
+      paint.setStrokeCap(Cap.BUTT);
+      arcBounds.set(-adjustedRadius, -adjustedRadius, adjustedRadius, adjustedRadius);
+      canvas.drawOval(arcBounds, paint);
+      return;
+    }
+
     // Sets up the paint.
     paint.setAntiAlias(true);
     paint.setColor(paintColor);