Fix zero radius arc bug, and add Inkscape documentation

web/help.html

@@ -30,6 +30,12 @@ <h2>Page settings</h2>
         intended placement. In that case it'll help to extend the canvas size inside Affinity to be square. Make sure to select "Anchor on page" to preserve your designs aspect ratio.
       </p>
 
+      <h3>Inkscape document scale</h3>
+      <p>If you're using Inkscape, set the document scale explicitly. Open <strong>File-&gt;Document Properties</strong>
+        and set the document <strong>Scale</strong> value to <code>0.01</code>, as shown here:</p>
+      <img src="./images/inkscape-document-properties.png">
+      <p>This ensures that measurements in your SVG correspond directly to millimeters in KiCAD and helps avoid scaling issues when converting your design.</p>
+
       <h2>Creating an outline</h2>
       <p>The outline should be drawn on a layer named <code>Edge.Cuts</code> in your vector editor. Gingerbread handles this layer in a specific way to make sure that there is a 1-to-1 match
         between the size and units in the SVG and KiCAD. This approach can't handle as many complex edge cases as the rasterization approach used by the graphic layers, but as

web/scripts/path-data-polyfill.js

@@ -1033,8 +1033,9 @@ if (!SVGPathElement.prototype.getPathData || !SVGPathElement.prototype.setPathDa
             ];
 
             // Get rid of redundant "A" segs when either rx or ry is 0
+            // (i.e. drop zero-radius arcs, keep everything else including the initial M).
             pathData = pathData.filter((s) => {
-                return s.type === "A" && (s.values[0] === 0 || s.values[1] === 0);
+                return !(s.type === "A" && (s.values[0] === 0 || s.values[1] === 0));
             });
 
             if (options && options.normalize === true) {

web/scripts/yak.js

@@ -275,9 +275,11 @@ export function* SVGElement_to_paths(elm) {
         for (const child of elm.children) {
             yield* SVGElement_to_paths(child);
         }
-    } else {
+    } else if (elm instanceof SVGGeometryElement || (elm.getPathData && typeof elm.getPathData === 'function')) {
+        // Only process elements that are geometry elements or have getPathData method
         yield* SVGGeometryElement_to_paths(elm);
     }
+    // Skip non-geometry elements like <defs>, <text>, <title>, etc.
 }
 
 /*