feat(history): add undo redo stack

editor/initial-state.ts

@@ -25,5 +25,6 @@ export function createInitialAppState(name = "Untitled"): AppState {
       assets: [],
     },
     editor: initialEditorState,
+    history: { past: [], future: [] },
   };
 }

editor/state.ts

@@ -23,7 +23,18 @@ export type EditorState = {
   transformSession?: TransformSession;
 };
 
-export type AppState = {
+export type HistorySnapshot = {
   document: ImageDocument;
   editor: EditorState;
 };
+
+export type HistoryState = {
+  past: HistorySnapshot[];
+  future: HistorySnapshot[];
+};
+
+export type AppState = {
+  document: ImageDocument;
+  editor: EditorState;
+  history: HistoryState;
+};