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/routers/word_router.py

@@ -34,18 +34,20 @@ def create_word(
 @router.get("", response_model=list[WordOut])
 def list_words(
     status: Optional[str] = None,
+    book_id: Optional[int] = None,
     db: Session = Depends(get_db),
     current_user: User = Depends(get_current_user),
 ):
-    return word_service.list_words(db, current_user, status)
+    return word_service.list_words(db, current_user, status, book_id=book_id)
 
 
 @router.get("/memory-viz", response_model=MemoryVisualizationResponse)
 def memory_visualization(
+    book_id: int = 0,
     db: Session = Depends(get_db),
     current_user: User = Depends(get_current_user),
 ):
-    return memory_visual_service.get_visualization(db, current_user)
+    return memory_visual_service.get_visualization(db, current_user, book_id=book_id)
 
 
 @router.get("/{word_id}/memory", response_model=WordMemoryDetailResponse)