initial implementation of edge toolbar

packages/system/src/utils/edge-toolbar.ts

@@ -0,0 +1,6 @@
+import { Position, type Viewport, type Align } from '..';
+
+export function getEdgeToolbarTransform(labelX: number, labelY: number, viewport: Viewport): string {
+  // Position the toolbar at the edge label center (scaling is handled by EdgeLabelRenderer)
+  return `translate(${labelX}px, ${labelY}px)`;
+}

packages/system/src/utils/index.ts

@@ -5,6 +5,7 @@ export * from './graph';
 export * from './general';
 export * from './marker';
 export * from './node-toolbar';
+export * from './edge-toolbar';
 export * from './store';
 export * from './types';
 export * from './shallow-node-data';