- 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