finish refactor pre merge

lib/editor/draft/useDraftState.ts

@@ -3,7 +3,9 @@ import type { FeatureCollection } from "@/types/geo";
 import { deepClone } from "@/lib/editor/draft/draftDiff";
 
 export function useDraftState(initialData: FeatureCollection) {
+    // Draft hiện tại (React state) để UI re-render khi dữ liệu thay đổi.
     const [draft, setDraft] = useState<FeatureCollection>(() => deepClone(initialData));
+    // Draft ref để đọc giá trị mới nhất trong event handlers/engines mà không cần deps.
     const draftRef = useRef<FeatureCollection>(deepClone(initialData));
 
     const commitDraft = useCallback((nextDraft: FeatureCollection) => {

lib/editor/draft/useUndoStack.ts

@@ -8,6 +8,7 @@ type Options = {
 
 export function useUndoStack(options: Options) {
     const { applyUndoAction } = options;
+    // Stack thao tác undo (append-only, pop khi undo).
     const [undoStack, setUndoStack] = useState<UndoAction[]>([]);
 
     const pushUndo = useCallback((action: UndoAction) => {