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/pages/CanvasView.tsx

@@ -1,6 +1,6 @@
 import { useState, useEffect, useCallback } from 'react';
 import { useNavigate, useParams, useSearchParams } from 'react-router-dom';
-import { ClipboardList, Download, Trash2, Layers, Home, ChevronRight, Save, RefreshCw, Zap, MessageSquare, X, Folder, SlidersHorizontal, Undo2, Redo2, CheckCircle } from 'lucide-react';
+import { ClipboardList, Download, Trash2, Layers, Home, ChevronRight, Save, RefreshCw, Zap, MessageSquare, X, Folder, SlidersHorizontal, Undo2, Redo2 } from 'lucide-react';
 import { AtomizerCanvas } from '../components/canvas/AtomizerCanvas';
 import { SpecRenderer } from '../components/canvas/SpecRenderer';
 import { NodePalette } from '../components/canvas/palette/NodePalette';
@@ -13,7 +13,7 @@ import { ChatPanel } from '../components/canvas/panels/ChatPanel';
 import { PanelContainer } from '../components/canvas/panels/PanelContainer';
 import { useCanvasStore } from '../hooks/useCanvasStore';
 import { useSpecStore, useSpec, useSpecLoading, useSpecIsDirty, useSelectedNodeId } from '../hooks/useSpecStore';
-import { usePanelStore } from '../hooks/usePanelStore';
+// usePanelStore is now used by child components - PanelContainer handles panels
 import { useSpecUndoRedo, useUndoRedoKeyboard } from '../hooks/useSpecUndoRedo';
 import { useStudy } from '../context/StudyContext';
 import { useChat } from '../hooks/useChat';