Add demo account database models

app/models.py

@@ -0,0 +1,38 @@
+from datetime import datetime, timezone
+from sqlalchemy import DateTime, Float, Integer, String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db import Base
+
+
+class DemoAccountState(Base):
+    __tablename__ = 'demo_account_state'
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, default=1)
+    quote_asset: Mapped[str] = mapped_column(String(16), nullable=False)
+    balance: Mapped[float] = mapped_column(Float, nullable=False)
+    equity: Mapped[float] = mapped_column(Float, nullable=False)
+    realized_pnl: Mapped[float] = mapped_column(Float, nullable=False, default=0.0)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        default=lambda: datetime.now(timezone.utc),
+        onupdate=lambda: datetime.now(timezone.utc),
+        nullable=False,
+    )
+
+
+class DemoTradeRecord(Base):
+    __tablename__ = 'demo_trades'
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    market: Mapped[str] = mapped_column(String(32), nullable=False, index=True)
+    side: Mapped[str] = mapped_column(String(8), nullable=False)
+    price: Mapped[float] = mapped_column(Float, nullable=False)
+    amount: Mapped[float] = mapped_column(Float, nullable=False)
+    quote_amount: Mapped[float] = mapped_column(Float, nullable=False)
+    reason: Mapped[str] = mapped_column(String(512), nullable=False)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        default=lambda: datetime.now(timezone.utc),
+        nullable=False,
+    )