docs: Comprehensive documentation update for Dashboard V3 and Canvas

## Documentation Updates
- DASHBOARD.md: Updated to V3.0 with Canvas V3 features, file browser, introspection
- DASHBOARD_IMPLEMENTATION_STATUS.md: Marked Canvas V3 features as COMPLETE
- CANVAS.md: New comprehensive guide for Canvas Builder V3 with all features
- CLAUDE.md: Added dashboard quick reference and Canvas V3 features

## Canvas V3 Features Documented
- File Browser: Browse studies directory for model files
- Model Introspection: Auto-discover expressions, solver type, dependencies
- One-Click Add: Add expressions as design variables instantly
- Claude Bug Fixes: WebSocket reconnection, SQL errors resolved
- Health Check: /api/health endpoint for monitoring

## Backend Services
- NX introspection service with expression discovery
- File browser API with type filtering
- Claude session management improvements
- Context builder enhancements

## Frontend Components
- FileBrowser: Modal for file selection with search
- IntrospectionPanel: View discovered model information
- ExpressionSelector: Dropdown for design variable configuration
- Improved chat hooks with reconnection logic

## Plan Documents
- Added RALPH_LOOP_CANVAS_V2/V3 implementation records
- Added ATOMIZER_DASHBOARD_V2_MASTER_PLAN
- Added investigation and sync documentation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -178,9 +178,28 @@ Atomizer/
 ├── studies/                 # User studies
 ├── tools/                   # CLI tools (archive_study.bat, zernike_html_generator.py)
 ├── archive/                 # Deprecated code (for reference)
-└── atomizer-dashboard/      # React dashboard
+└── atomizer-dashboard/      # React dashboard (V3.0)
+    ├── frontend/            # React + Vite + Tailwind
+    │   └── src/components/canvas/   # Canvas Builder with 8 node types
+    └── backend/api/         # FastAPI + SQLite
+        ├── services/        # claude_agent, nx_introspection, session_manager
+        └── routes/          # files, nx, terminal, optimization
 ```
 
+### Dashboard Quick Reference
+
+| Feature | Documentation |
+|---------|--------------|
+| **Canvas Builder** | `docs/04_USER_GUIDES/CANVAS.md` |
+| **Dashboard Overview** | `docs/04_USER_GUIDES/DASHBOARD.md` |
+| **Implementation Status** | `docs/04_USER_GUIDES/DASHBOARD_IMPLEMENTATION_STATUS.md` |
+
+**Canvas V3 Features:**
+- File browser for model selection
+- Model introspection (expressions, solver type, dependencies)
+- One-click add expressions as design variables
+- Claude chat integration with WebSocket
+
 ### Import Migration (v2.0)
 Old imports still work with deprecation warnings. New paths:
 ```python