feat: MTG database integration with Redis caching

- Added MTG card ORM models (mtg_cards, mtg_sets tables)
- Created card_database service with search, get_by_name, get_by_set
- Added Redis client with caching layer (3600s TTL default)
- Created card router with caching on all endpoints:
  - Search cards (5min cache)
  - Get card by name (10min cache)
  - Get cards by set (15min cache)
  - Get card types/rarities (30min cache)
  - Get sets (1hr cache)
  - Get statistics (1hr cache)
- Updated settings.py:
  - Added JWT_SECRET_KEY field
  - Added DB_CONFIG and REDIS_CONFIG dictionaries
- Updated security.py to use JWT_SECRET_KEY with fallback
- Updated auth.py to use timezone-aware datetimes
- Updated refresh_mtg.py to use settings instead of os.environ
- Updated mtg_monitor.py to use settings for connections
- Added services package with __init__.py

All 20 tests passing.

backend/app/models/mtg_models.py

@@ -0,0 +1,71 @@
+"""
+SQLAlchemy ORM models for the MTG database (mtgjson.com data).
+
+Models mirror the mtg_cards and mtg_sets tables in the MTG PostgreSQL database.
+"""
+from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey, Index
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+from app.core.database import Base
+
+
+class MtgSet(Base):
+    """MTG Set model."""
+    __tablename__ = "mtg_sets"
+
+    id = Column(Integer, primary_key=True, index=True)
+    code = Column(String(10), unique=True, nullable=False, index=True)
+    name = Column(String(255), nullable=True)
+    type = Column(String(100), nullable=True)
+    release_date = Column(DateTime, nullable=True)
+    base_set_size = Column(Integer, nullable=True)
+    total_size = Column(Integer, nullable=True)
+    is_foil_only = Column(Integer, nullable=True)
+    is_non_foil_only = Column(Integer, nullable=True)
+    digital = Column(Integer, nullable=True)
+    icon_svg_url = Column(Text, nullable=True)
+    parent_code = Column(String(10), nullable=True)
+    mtgo_code = Column(String(10), nullable=True)
+    created_at = Column(DateTime, server_default=func.now())
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())
+
+    # Relationships
+    cards = relationship("MtgCard", back_populates="set")
+
+    def __repr__(self) -> str:
+        return f"<MtgSet {self.code}: {self.name}>"
+
+
+class MtgCard(Base):
+    """MTG Card model."""
+    __tablename__ = "mtg_cards"
+
+    id = Column(Integer, primary_key=True, index=True)
+    set_id = Column(Integer, ForeignKey("mtg_sets.id"), nullable=True, index=True)
+    name = Column(String(255), nullable=True, index=True)
+    mana_cost = Column(String(255), nullable=True, index=True)
+    type_line = Column(String(255), nullable=True, index=True)
+    oracle_text = Column(Text, nullable=True)
+    power = Column(String(50), nullable=True)
+    toughness = Column(String(50), nullable=True)
+    rarity = Column(String(50), nullable=True, index=True)
+    layout = Column(String(50), nullable=True)
+    artist = Column(String(255), nullable=True)
+    flavor_text = Column(Text, nullable=True)
+    numbers = Column(String(100), nullable=True)
+    identifiers = Column(Text, nullable=True)  # JSON string
+    images = Column(Text, nullable=True)  # JSON string
+    created_at = Column(DateTime, server_default=func.now())
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())
+
+    # Relationships
+    set = relationship("MtgSet", back_populates="cards")
+
+    def __repr__(self) -> str:
+        return f"<MtgCard {self.name} ({self.set_id})>"
+
+
+# Indexes for performance
+Index("idx_mtg_cards_name_set", MtgCard.name, MtgCard.set_id)
+Index("idx_mtg_cards_type", MtgCard.type_line)
+Index("idx_mtg_cards_rarity", MtgCard.rarity)