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/shared/novel-pack.ts

@@ -0,0 +1,40 @@
+export const NOVEL_FORMAT_VERSION = 1
+export const NOVEL_ALL_FORMAT_VERSION = 1
+
+export interface NovelManifest {
+  formatVersion: number
+  appVersion: string
+  exportedAt: string
+  bookId: string
+  bookName: string
+}
+
+export interface NovelAllManifest {
+  formatVersion: number
+  appVersion: string
+  exportedAt: string
+  bookCount: number
+}
+
+export type PackImportStrategy = 'skip' | 'overwrite' | 'new'
+
+export interface PackImportBookResult {
+  sourceBookId: string
+  targetBookId: string | null
+  bookName: string
+  action: 'imported' | 'skipped' | 'overwritten'
+}
+
+export interface PackImportReport {
+  imported: number
+  skipped: number
+  overwritten: number
+  books: PackImportBookResult[]
+}
+
+export interface PackProgressEvent {
+  current: number
+  total: number
+  phase: 'export' | 'import' | 'estimate'
+  message?: string
+}