feat(editor): visible feedback for Test run — status pill + View link

Before, the Test run button fired and returned an execution id but there was
no on-screen confirmation, so users assumed nothing happened. Adds an inline
status bar under the toolbar that shows 'Running…', then either 'Started
execution <id> · View execution →' (auto-clears in 6s) or 'Test run failed:
<msg>' (auto-clears in 8s).

frontend/src/pages/EditorPage.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useMemo, useState } from "react";
+import { useEffect, useMemo, useRef, useState } from "react";
 import { Link, useParams } from "react-router-dom";
 import type { Edge, Node } from "@xyflow/react";
 import { useNodeTypes, useWorkflow } from "@/api/hooks";
@@ -82,6 +82,19 @@ export default function EditorPage() {
     () => apiFetch<void>(`/api/workflows/${id}/deactivate`, { method: "POST" }),
     { onSuccess: () => id && invalidate(qk.workflow(id)) },
   );
+  const [testStatus, setTestStatus] = useState<
+    | { kind: "idle" }
+    | { kind: "running" }
+    | { kind: "success"; executionId: string }
+    | { kind: "error"; message: string }
+  >({ kind: "idle" });
+  const clearTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
+  useEffect(() => () => { if (clearTimer.current) clearTimeout(clearTimer.current); }, []);
+  function scheduleClear(ms: number) {
+    if (clearTimer.current) clearTimeout(clearTimer.current);
+    clearTimer.current = setTimeout(() => setTestStatus({ kind: "idle" }), ms);
+  }
+
   const testRun = useApiMutation(
     () => {
       const triggers = nodes.filter((n) =>
@@ -93,6 +106,17 @@ export default function EditorPage() {
         { method: "POST", body: { startFromNodeId: startFrom, triggerData: {} } },
       );
     },
+    {
+      onMutate: () => setTestStatus({ kind: "running" }),
+      onSuccess: (res) => {
+        setTestStatus({ kind: "success", executionId: res.executionId });
+        scheduleClear(6000);
+      },
+      onError: (err) => {
+        setTestStatus({ kind: "error", message: err instanceof Error ? err.message : String(err) });
+        scheduleClear(8000);
+      },
+    },
   );
 
   if (wf.isLoading || !wf.data) {
@@ -144,6 +168,33 @@ export default function EditorPage() {
           )}
         </div>
       </div>
+      {testStatus.kind !== "idle" && (
+        <div
+          role="status"
+          className={
+            "px-4 py-2 text-sm border-b flex items-center gap-2 " +
+            (testStatus.kind === "success"
+              ? "bg-emerald-950/50 border-emerald-900 text-emerald-200"
+              : testStatus.kind === "error"
+                ? "bg-red-950/50 border-red-900 text-red-200"
+                : "bg-slate-900 border-slate-800 text-slate-300")
+          }
+        >
+          {testStatus.kind === "running" && <>Running test execution…</>}
+          {testStatus.kind === "success" && (
+            <>
+              Started execution <code className="font-mono text-xs">{testStatus.executionId}</code>
+              <Link
+                to={`/workflows/${id}/executions`}
+                className="ml-auto underline hover:text-emerald-100"
+              >
+                View execution →
+              </Link>
+            </>
+          )}
+          {testStatus.kind === "error" && <>Test run failed: {testStatus.message}</>}
+        </div>
+      )}
       <div className="flex-1 flex">
         <NodePalette />
         <div className="flex-1">