feat(w2): add PackService for .novel and .novel-all export/import

Introduce pack-bootstrap chunk, ZipArchive-based PackService with progress IPC,
book registry import helpers, and IT-PACK-01 / IT-ALL-02 integration tests.

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

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

@@ -0,0 +1,81 @@
+import { dialog, ipcMain } from 'electron'
+import { IPC } from '../../../shared/ipc-channels'
+import type { PackImportStrategy } from '../../../shared/novel-pack'
+import { PackService } from '../../services/pack.service'
+import type { BookRegistryService } from '../../services/book-registry'
+import type { GlobalSettingsService } from '../../services/global-settings'
+import { wrap } from '../result'
+
+let packService: PackService | null = null
+
+function svc(registry: BookRegistryService, settings: GlobalSettingsService): PackService {
+  if (!packService) {
+    packService = new PackService(registry, settings, registry.getUserDataDir())
+  }
+  return packService
+}
+
+export function registerPackHandlers(
+  registry: BookRegistryService,
+  settings: GlobalSettingsService
+): void {
+  const service = () => svc(registry, settings)
+
+  ipcMain.handle(
+    IPC.PACK_EXPORT_BOOK,
+    (_e, { bookId, destPath }: { bookId: string; destPath: string }) =>
+      wrap(() => service().exportBook(bookId, destPath))
+  )
+
+  ipcMain.handle(IPC.PACK_IMPORT_BOOK, (_e, { filePath }: { filePath: string }) =>
+    wrap(() => service().importBook(filePath))
+  )
+
+  ipcMain.handle(IPC.PACK_EXPORT_ALL, (_e, { destPath }: { destPath: string }) =>
+    wrap(() => service().exportAll(destPath))
+  )
+
+  ipcMain.handle(
+    IPC.PACK_IMPORT_ALL,
+    (_e, { filePath, strategy }: { filePath: string; strategy: PackImportStrategy }) =>
+      wrap(() => service().importAll(filePath, strategy))
+  )
+
+  ipcMain.handle(IPC.PACK_ESTIMATE_EXPORT_ALL, () =>
+    wrap(() => ({
+      bytes: service().estimateExportAllBytes(),
+      needsConfirm: service().needsExportAllConfirm()
+    }))
+  )
+
+  ipcMain.handle(IPC.PACK_NEEDS_CONFIRM, () =>
+    wrap(() => service().needsExportAllConfirm())
+  )
+
+  ipcMain.handle(IPC.PACK_CANCEL, () =>
+    wrap(() => {
+      service().cancel()
+    })
+  )
+
+  ipcMain.handle(IPC.PACK_PICK_FILE, (_e, { mode }: { mode: 'novel' | 'novel-all' | 'save-novel' | 'save-all' }) =>
+    wrap(async () => {
+      if (mode === 'save-novel' || mode === 'save-all') {
+        const ext = mode === 'save-all' ? 'novel-all' : 'novel'
+        const { canceled, filePath } = await dialog.showSaveDialog({
+          filters: [{ name: 'Bilin Pack', extensions: [ext] }],
+          defaultPath: mode === 'save-all' ? 'bilin-backup.novel-all' : 'book.novel'
+        })
+        if (canceled || !filePath) return null
+        return filePath
+      }
+      const extensions = mode === 'novel-all' ? ['novel-all'] : ['novel', 'novel-all']
+      const { canceled, filePaths } = await dialog.showOpenDialog({
+        properties: ['openFile'],
+        filters: [{ name: 'Bilin Pack', extensions }]
+      })
+      if (canceled || filePaths.length === 0) return null
+      return filePaths[0]
+    })
+  )
+}