Add word-book practice, iOS app shell, and fix embedded WebView blank screen.

Ship dual-track learning (daily accumulation vs textbook),沪教/商务词书 APIs and UI, native iOS wrapper with bundled H5, and production book import on deploy.

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

backend/main.py

@@ -5,6 +5,7 @@ from database import Base, engine
 from db_migrate import run_migrations
 from routers import (
     auth_router,
+    book_router,
     coach_router,
     quiz_router,
     settings_router,
@@ -27,6 +28,7 @@ app.add_middleware(
 
 app.include_router(auth_router.router)
 app.include_router(translate_router.router)
+app.include_router(book_router.router)
 app.include_router(word_router.router)
 app.include_router(quiz_router.router)
 app.include_router(settings_router.router)