Phase 2.1: Card mirror system for deckbuilding features

- Created MtgCardMirror and DeckCardLink models in mirror_models.py
- Created card_mirror_service.py with sync_mirrors functionality
- Added sync_mirrors() method to mtgjson_manager.py
- Added mirror_get_db() dependency to database.py
- Added DecklistFile.status column (DRAUGHT/FINAL)
- Updated DeckCreate schema with status field
- Added DeckWithCardsResponse schema with card_count
- Updated deck router to query card mirrors and return card counts
- Added plain text deck content support

backend/app/core/database.py

@@ -40,13 +40,9 @@ mtg_async_session = async_sessionmaker(
     expire_on_commit=False,
 )
 
-
-class Base(DeclarativeBase):
-    """Base class for all ORM models."""
-    pass
-
-
-__all__ = ["Base", "get_db", "async_session", "engine", "mtg_get_db", "mtg_async_session", "mtg_engine"]
+# Mirror engine (same as primary — mirrors live in mtgo_platform)
+mirror_engine = engine
+mirror_async_session = async_session
 
 
 async def get_db() -> AsyncSession:
@@ -73,3 +69,35 @@ async def mtg_get_db() -> AsyncSession:
             raise
         finally:
             await session.close()
+
+
+async def mirror_get_db() -> AsyncSession:
+    """FastAPI dependency that provides a database session for mirror operations."""
+    async with mirror_async_session() as session:
+        try:
+            yield session
+            await session.commit()
+        except Exception:
+            await session.rollback()
+            raise
+        finally:
+            await session.close()
+
+
+class Base(DeclarativeBase):
+    """Base class for all ORM models."""
+    pass
+
+
+__all__ = [
+    "Base",
+    "get_db",
+    "async_session",
+    "engine",
+    "mtg_get_db",
+    "mtg_async_session",
+    "mtg_engine",
+    "mirror_get_db",
+    "mirror_async_session",
+    "mirror_engine",
+]