Add workflow editor and node types support in frontend and backend

- Introduce a new workflow editor component for visualizing and managing workflows, allowing users to add nodes and define connections.
- Implement backend support for node types, including validation and constraints for workflow graphs.
- Add new API endpoints for retrieving node types and their specifications.
- Enhance the AssistantPage to integrate the workflow editor, enabling users to create and edit workflows directly.
- Update frontend components to support new workflow functionalities, including condition edges and generic nodes.
- Refactor existing code to accommodate the new workflow features and improve overall structure.

backend/app.py

@@ -24,6 +24,7 @@ from routes import (
     health,
     knowledge_bases,
     model_registry,
+    node_types,
     voice_webrtc,
     voice_ws,
 )
@@ -49,6 +50,7 @@ app.include_router(health.router)
 app.include_router(assistants.router)
 app.include_router(knowledge_bases.router)
 app.include_router(model_registry.router)
+app.include_router(node_types.router)
 app.include_router(voice_webrtc.router)
 app.include_router(voice_ws.router)