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>

e2e/helpers.ts

@@ -61,3 +61,19 @@ export async function openExportModal(page: Page): Promise<void> {
   }
   await expect(modal).toBeVisible({ timeout: 10_000 })
 }
+
+export async function openBookSettings(page: Page): Promise<void> {
+  await page.getByTestId('panel-tab-book-settings').click()
+  await expect(page.getByTestId('book-settings-tab')).toBeVisible({ timeout: 10_000 })
+}
+
+export async function addCharacterSetting(page: Page, name: string): Promise<void> {
+  await page.getByTestId('sidebar-tab-setting').click()
+  await page.getByTestId('setting-new').click()
+  await page.getByTestId('setting-name-input').fill(name)
+  await page.locator('.dialog-content select').selectOption('character')
+  await page.getByRole('button', { name: '创建' }).click()
+  await expect(page.getByTestId(/setting-item-/).filter({ hasText: name })).toBeVisible({
+    timeout: 10_000
+  })
+}