feat(preview): make address bar interactive for routing inside iframe

vibn-frontend/app/[workspace]/project/[projectId]/(home)/preview/page.tsx

@@ -152,6 +152,7 @@ export default function PreviewTab() {
 
   const deviceMode = usePreviewToolbarStore((s) => s.deviceMode);
   const refreshKey = usePreviewToolbarStore((s) => s.refreshKey);
+  const currentPath = usePreviewToolbarStore((s) => s.currentPath);
 
   // When the user clicks the manual refresh button in the toolbar, we don't
   // just want to reload the iframe — we also want to trigger the same ghost/zombie
@@ -166,8 +167,16 @@ export default function PreviewTab() {
   }, [refreshKey]);
 
   useLayoutEffect(() => {
-    setIframeSrc(primaryRunning?.url ?? null);
-  }, [primaryRunning?.url]);
+    if (!primaryRunning?.url) {
+      setIframeSrc(null);
+    } else {
+      const base = primaryRunning.url.replace(/\/$/, "");
+      const path = currentPath.startsWith("/")
+        ? currentPath
+        : `/${currentPath}`;
+      setIframeSrc(`${base}${path}`);
+    }
+  }, [primaryRunning?.url, currentPath]);
 
   useEffect(() => {
     if (!bridge || !iframeSrc || !iframeDomRef.current) return;