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.

frontend/src/components/ui/sheet.tsx

@@ -50,14 +50,16 @@ function SheetContent({
   children,
   side = "right",
   showCloseButton = true,
+  showOverlay = true,
   ...props
 }: React.ComponentProps<typeof SheetPrimitive.Content> & {
   side?: "top" | "right" | "bottom" | "left"
   showCloseButton?: boolean
+  showOverlay?: boolean
 }) {
   return (
     <SheetPortal>
-      <SheetOverlay />
+      {showOverlay && <SheetOverlay />}
       <SheetPrimitive.Content
         data-slot="sheet-content"
         data-side={side}