feat: Add WebSocket live updates and convergence visualization

Phase 4 - Live Updates:
- Create useOptimizationStream hook for real-time trial updates
- Replace polling with WebSocket subscription in SpecRenderer
- Auto-report errors to ErrorPanel via panel store
- Add progress tracking (FEA count, NN count, best trial)

Phase 5 - Convergence Visualization:
- Add ConvergenceSparkline component for mini line charts
- Add ProgressRing component for circular progress indicator
- Update ObjectiveNode to show convergence trend sparkline
- Add history field to ObjectiveNodeData schema
- Add live progress indicator centered on canvas when running

Bug fixes:
- Fix TypeScript errors in FloatingIntrospectionPanel (type casts)
- Fix ValidationPanel using wrong store method (selectNode vs setSelectedNodeId)
- Fix NodeConfigPanelV2 unused state variable
- Fix specValidator source.extractor_id path
- Clean up unused imports across components

atomizer-dashboard/frontend/src/components/canvas/panels/NodeConfigPanelV2.tsx

@@ -43,7 +43,6 @@ export function NodeConfigPanelV2({ onClose }: NodeConfigPanelV2Props) {
   const { updateNode, removeNode, clearSelection } = useSpecStore();
   
   const [showFileBrowser, setShowFileBrowser] = useState(false);
-  const [showIntrospection, setShowIntrospection] = useState(false);
   const [isUpdating, setIsUpdating] = useState(false);
   const [error, setError] = useState<string | null>(null);
 
@@ -249,16 +248,7 @@ export function NodeConfigPanelV2({ onClose }: NodeConfigPanelV2Props) {
         fileTypes={['.sim', '.prt', '.fem', '.afem']}
       />
 
-      {/* Introspection Panel */}
-      {showIntrospection && spec.model.sim?.path && (
-        <div className="fixed top-20 right-96 z-40">
-          <IntrospectionPanel
-            filePath={spec.model.sim.path}
-            studyId={useSpecStore.getState().studyId || undefined}
-            onClose={() => setShowIntrospection(false)}
-          />
-        </div>
-      )}
+      {/* Introspection is now handled by FloatingIntrospectionPanel via usePanelStore */}
     </div>
   );
 }
@@ -280,6 +270,7 @@ function ModelNodeConfig({ spec }: SpecConfigProps) {
       filePath: spec.model.sim?.path || '',
       studyId: useSpecStore.getState().studyId || undefined,
     });
+    openPanel('introspection');
   };
   
   return (