fix(sticky): fixed-size creation, shared presets module, live resize sync

Fixes three review findings:

1. Sticky creation no longer zoom-adapts — always creates at M preset
   (28px/260w) in world space. Consistent at any zoom level.

2. Preset definitions extracted to stickyPresets.ts (shared domain module).
   TextFormatToolbar and tools.ts both import from there — no more
   canvas→component dependency inversion.

3. TextEditor.onLiveResize callback syncs spatial index and transform
   box as sticky background grows during typing.

frontend/src/hooks/useCanvasSetup.ts

@@ -130,6 +130,9 @@ export function useCanvasSetup(deps: CanvasSetupDeps) {
           }
           syncRef.current?.broadcastElements([item.id]);
           onCanvasChange();
+        }, (resizedItem) => {
+          scene.updateSpatialEntry(resizedItem);
+          selection.transformBox.update([resizedItem]);
         });
       };