ENG-1546: Implement relation creation via drag handles in tldraw (Roam)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: trangdoan982

apps/roam/src/components/canvas/Tldraw.tsx

@@ -55,6 +55,7 @@ import {
 } from "tldraw";
 import "tldraw/tldraw.css";
 import tldrawStyles from "./tldrawStyles";
+import { DragHandleOverlay } from "./overlays/DragHandleOverlay";
 import getDiscourseNodes, { DiscourseNode } from "~/utils/getDiscourseNodes";
 import getDiscourseRelations, {
   DiscourseRelation,
@@ -666,6 +667,7 @@ const TldrawCanvasShared = ({
   const editorComponents: TLEditorComponents = {
     ...defaultEditorComponents,
     OnTheCanvas: ToastListener,
+    InFrontOfTheCanvas: DragHandleOverlay,
   };
   const customUiComponents: TLUiComponents = createUiComponents({
     allNodes,