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>

tests/main/migrate-v9.test.ts

@@ -0,0 +1,23 @@
+import { describe, it, expect, afterEach } from 'vitest'
+import { DatabaseSync } from 'node:sqlite'
+import { migrate } from '../../src/main/db/migrate'
+import type { SqliteDb } from '../../src/main/db/types'
+
+describe('migrate v9', () => {
+  let db: SqliteDb
+  afterEach(() => db?.close())
+
+  it('UT-MIG-09: fresh database migrates to v9 with chapter_tags', () => {
+    db = new DatabaseSync(':memory:')
+    migrate(db)
+    const version = db.prepare('SELECT MAX(version) AS v FROM schema_version').get() as { v: number }
+    expect(version.v).toBe(9)
+    const table = db
+      .prepare("SELECT name FROM sqlite_master WHERE type='table' AND name='chapter_tags'")
+      .get()
+    expect(table).toBeTruthy()
+    const chapterCols = db.prepare('PRAGMA table_info(chapters)').all() as Array<{ name: string }>
+    expect(chapterCols.some((c) => c.name === 'published_at')).toBe(true)
+    expect(chapterCols.some((c) => c.name === 'word_count_threshold')).toBe(true)
+  })
+})