fix(builder): Show X button on edge line hover, not just button hover

Add invisible interaction path along edge that triggers hover state,
making the remove button appear when hovering anywhere on the connection
line rather than requiring users to find the small button directly.

Fixes SECRT-1943

autogpt_platform/frontend/src/app/(platform)/build/components/FlowEditor/edges/CustomEdge.tsx

@@ -63,6 +63,16 @@ const CustomEdge = ({
 
   return (
     <>
+      {/* Invisible interaction path - wider hit area for hover detection */}
+      <path
+        d={edgePath}
+        fill="none"
+        stroke="transparent"
+        strokeWidth={20}
+        className="cursor-pointer"
+        onMouseEnter={() => setIsHovered(true)}
+        onMouseLeave={() => setIsHovered(false)}
+      />
       <BaseEdge
         path={edgePath}
         markerEnd={markerEnd}