feat: Jump to Error centers the failed node in the viewport

Added centerOnNodeId prop to ProcessDiagram. When set, the diagram
pans to center the specified node in the viewport. Jump to Error
now selects the failed processor AND centers the viewport on it.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/components/ExecutionDiagram/ExecutionDiagram.tsx

@@ -80,8 +80,9 @@ export function ExecutionDiagram({
   // 4. Compute overlay
   const overlay = useExecutionOverlay(detail?.processors, iterationState);
 
-  // 5. Manage selection
+  // 5. Manage selection + center-on-node
   const [selectedProcessorId, setSelectedProcessorId] = useState<string>('');
+  const [centerOnNodeId, setCenterOnNodeId] = useState<string>('');
 
   // 6. Resizable splitter state
   const [splitPercent, setSplitPercent] = useState(60);
@@ -105,12 +106,15 @@ export function ExecutionDiagram({
     document.addEventListener('pointerup', onUp);
   }, []);
 
-  // Jump to error: find first FAILED processor and select it
+  // Jump to error: find first FAILED processor, select it, and center the viewport
   const handleJumpToError = useCallback(() => {
     if (!detail?.processors) return;
     const failed = findFailedProcessor(detail.processors);
     if (failed?.processorId) {
       setSelectedProcessorId(failed.processorId);
+      // Use a unique value to re-trigger centering even if the same node
+      setCenterOnNodeId('');
+      requestAnimationFrame(() => setCenterOnNodeId(failed.processorId));
     }
   }, [detail?.processors]);
 
@@ -187,6 +191,7 @@ export function ExecutionDiagram({
           executionOverlay={overlay}
           iterationState={iterationState}
           onIterationChange={setIteration}
+          centerOnNodeId={centerOnNodeId}
         />
       </div>