feat: add card import feature with fuzzy matching

- Add UserCardImport model (stores imported card names as JSON)
- Create card_import_schemas.py with request/response models
- Create card_import.py router with import/get/delete endpoints
- Add Alembic migration 004 (user_card_imports table)
- Fuzzy matching for card name matching (60% threshold)
- Integration with deckbuilding via imported cards
- Endpoints: GET /api/v1/card-import/status, POST /, DELETE /, GET /summary

backend/app/models/__init__.py

@@ -9,6 +9,7 @@ from app.models.user_data import (
     NetworkMember, UserPreference, UserActivityLog
 )
 from app.models.user_deck import UserDeck, UserDeckCard, DeckPrecedent, DeckPrecedentCard, CardSuggestion
+from app.models.user_card_import import UserCardImport
 
 __all__ = [
     "User",
@@ -43,4 +44,6 @@ __all__ = [
     "DeckPrecedent",
     "DeckPrecedentCard",
     "CardSuggestion",
+    "UserCardCollection",
+    "UserCardImport",
 ]