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-v3.test.ts

@@ -25,7 +25,7 @@ describe('migrate v3', () => {
     expect(tableExists(db, 'ai_messages')).toBe(true)
 
     const version = db.prepare('SELECT MAX(version) AS v FROM schema_version').get() as { v: number }
-    expect(version.v).toBe(8)
+    expect(version.v).toBe(9)
   })
 
   it('migrates existing v2 database to v3', () => {
@@ -49,6 +49,6 @@ describe('migrate v3', () => {
     expect(tables.map((t) => t.name)).toContain('ai_messages')
 
     const version = db.prepare('SELECT MAX(version) AS v FROM schema_version').get() as { v: number }
-    expect(version.v).toBe(8)
+    expect(version.v).toBe(9)
   })
 })