feat: ship v1.2.0 Wave 1 foundation with book settings, chapter management, and focus mode

Deliver schema v9, book/chapter IPC extensions, BookSettingsTab, chapter meta/tags,
AI session menu, focus mode and TTS, template context enrich, and Wave 1 E2E coverage.

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

src/shared/ipc-channels.ts

@@ -6,6 +6,7 @@ export const IPC = {
   BOOK_DELETE: 'book:delete',
   BOOK_OPEN: 'book:open',
   BOOK_UPDATE_META: 'book:updateMeta',
+  BOOK_PICK_COVER: 'book:pickCover',
   VOLUME_CREATE: 'volume:create',
   VOLUME_UPDATE: 'volume:update',
   VOLUME_DELETE: 'volume:delete',
@@ -143,5 +144,11 @@ export const IPC = {
   BRIDGE_GET: 'bridge:get',
   BRIDGE_DISMISS: 'bridge:dismiss',
   BRIDGE_SHOULD_PROMPT: 'bridge:shouldPrompt',
-  CHAPTER_SET_PUBLISH_STATUS: 'chapter:setPublishStatus'
+  CHAPTER_SET_PUBLISH_STATUS: 'chapter:setPublishStatus',
+  CHAPTER_TAG_LIST: 'chapter:tagList',
+  CHAPTER_TAG_SET: 'chapter:tagSet',
+  CHAPTER_TAG_REMOVE: 'chapter:tagRemove',
+  BOOK_PREFS_GET: 'book:prefsGet',
+  BOOK_PREFS_SET: 'book:prefsSet',
+  AI_SESSION_EXPORT: 'ai:sessionExport'
 } as const