feat(io): save and open .margin projects with cmd-s and cmd-o

src/store/useBook.ts

@@ -5,11 +5,14 @@ import { type Book, createChapter, starterBook } from "../model/book";
 interface BookState {
   book: Book;
   activeChapterId: string;
+  path: string | null;
   dirty: boolean;
   setActiveChapter: (id: string) => void;
   setChapterContent: (id: string, content: JSONContent) => void;
   setChapterTitle: (id: string, title: string) => void;
   addChapter: () => void;
+  replaceBook: (book: Book, path: string) => void;
+  markSaved: (path: string) => void;
 }
 
 export const useBook = create<BookState>((set) => {
@@ -17,6 +20,7 @@ export const useBook = create<BookState>((set) => {
   return {
     book,
     activeChapterId: book.chapters[0].id,
+    path: null,
     dirty: false,
     setActiveChapter: (id) => set({ activeChapterId: id }),
     setChapterContent: (id, content) =>
@@ -44,5 +48,8 @@ export const useBook = create<BookState>((set) => {
           book: { ...s.book, chapters: [...s.book.chapters, chapter] },
         };
       }),
+    replaceBook: (book, path) =>
+      set({ book, activeChapterId: book.chapters[0]?.id ?? "", path, dirty: false }),
+    markSaved: (path) => set({ path, dirty: false }),
   };
 });