feat(w5): ship v2.0.0 platform sync, undo persistence, and updates

Co-authored-by: Cursor <cursoragent@cursor.com>

src/main/ipc/handlers/undo.handler.ts

@@ -0,0 +1,36 @@
+import { ipcMain } from 'electron'
+import { IPC } from '../../../shared/ipc-channels'
+import type { UndoOperation } from '../../../shared/undo'
+import { UndoStackService } from '../../services/undo-stack.service'
+import type { BookRegistryService } from '../../services/book-registry'
+import { wrap } from '../result'
+
+export function registerUndoHandlers(registry: BookRegistryService): void {
+  ipcMain.handle(
+    IPC.UNDO_PUSH,
+    (
+      _e,
+      {
+        bookId,
+        chapterId,
+        operation
+      }: { bookId: string; chapterId: string; operation: UndoOperation }
+    ) => wrap(() => new UndoStackService(registry.getDb(bookId)).push(chapterId, operation))
+  )
+
+  ipcMain.handle(
+    IPC.UNDO_LIST,
+    (_e, { bookId, chapterId }: { bookId: string; chapterId: string }) =>
+      wrap(() => new UndoStackService(registry.getDb(bookId)).list(chapterId))
+  )
+
+  ipcMain.handle(
+    IPC.UNDO_APPLY,
+    (_e, { bookId, entryId }: { bookId: string; entryId: number }) =>
+      wrap(() => {
+        const op = new UndoStackService(registry.getDb(bookId)).apply(entryId)
+        if (!op) throw new Error('Undo entry not found')
+        return op
+      })
+  )
+}