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/lib/canvas/schema.ts

@@ -99,6 +99,7 @@ export interface ObjectiveNodeData extends BaseNodeData {
   extractorRef?: string;  // Reference to extractor ID
   outputName?: string;    // Which output from the extractor
   penaltyWeight?: number; // For hard constraints (penalty method)
+  history?: number[];     // Recent values for sparkline visualization
 }
 
 export interface ConstraintNodeData extends BaseNodeData {