POL-9: Add fees table

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/models/fee.py

@@ -0,0 +1,25 @@
+import uuid
+from datetime import datetime
+from decimal import Decimal
+
+from sqlalchemy import DateTime, ForeignKey, Numeric, Text, Uuid, func
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.database import Base
+
+
+class Fee(Base):
+    __tablename__ = "fees"
+
+    id: Mapped[uuid.UUID] = mapped_column(Uuid(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    championship_id: Mapped[uuid.UUID] = mapped_column(Uuid(as_uuid=True), ForeignKey("championships.id", ondelete="CASCADE"), nullable=False, unique=True)
+    video_selection: Mapped[Decimal | None] = mapped_column(Numeric(10, 2))  # video review/selection fee
+    solo: Mapped[Decimal | None] = mapped_column(Numeric(10, 2))
+    duet: Mapped[Decimal | None] = mapped_column(Numeric(10, 2))
+    group: Mapped[Decimal | None] = mapped_column(Numeric(10, 2))
+    refund_note: Mapped[str | None] = mapped_column(Text)
+
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())
+
+    championship: Mapped["Championship"] = relationship(back_populates="fees")  # type: ignore[name-defined]