fix(webui): restore fork action icon

webui/src/components/MessageBubble.tsx

@@ -11,7 +11,6 @@ import {
   ChevronRight,
   Clock3,
   Copy,
-  GitFork,
   ImageIcon,
   Sparkles,
   Wrench,
@@ -52,6 +51,26 @@ interface MessageBubbleProps {
   onForkFromHere?: () => void;
 }
 
+function ForkArrowIcon({ className }: { className?: string }) {
+  return (
+    <svg
+      viewBox="0 0 24 24"
+      fill="none"
+      stroke="currentColor"
+      strokeWidth="2"
+      strokeLinecap="round"
+      strokeLinejoin="round"
+      className={className}
+      aria-hidden
+    >
+      <path d="M5 19c8 0 8-14 16-14" />
+      <path d="M14 5h7v7" />
+      <path d="M5 5c5 0 7 3 9 7" />
+      <path d="M14 12h5v-5" />
+    </svg>
+  );
+}
+
 /**
  * Render a single message. Following agent-chat-ui: user turns are a rounded
  * "pill" right-aligned with a muted fill; assistant turns render as bare
@@ -231,7 +250,7 @@ export function MessageBubble({
                           "focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring",
                         )}
                       >
-                        <GitFork className="h-4 w-4" aria-hidden />
+                        <ForkArrowIcon className="h-4 w-4" />
                       </button>
                     </TooltipTrigger>
                     <TooltipContent side="top" align="center">{forkLabel}</TooltipContent>