refactor: removed nullable in models

models/deal.py

@@ -14,20 +14,19 @@ if TYPE_CHECKING:
 class Deal(BaseModel, IdMixin, SoftDeleteMixin, CreatedAtMixin):
     __tablename__ = "deals"
 
-    name: Mapped[str] = mapped_column(nullable=False)
-    lexorank: Mapped[str] = mapped_column(nullable=False)
+    name: Mapped[str] = mapped_column()
+    lexorank: Mapped[str] = mapped_column()
 
     status_id: Mapped[int] = mapped_column(
         ForeignKey("statuses.id"),
-        nullable=False,
         comment="Текущий статус",
     )
     status: Mapped["Status"] = relationship()
 
-    board_id: Mapped[int] = mapped_column(
-        ForeignKey("boards.id"), nullable=True, server_default="1"
+    board_id: Mapped[Optional[int]] = mapped_column(
+        ForeignKey("boards.id"), server_default="1"
     )
-    board: Mapped["Board"] = relationship(back_populates="deals")
+    board: Mapped[Optional["Board"]] = relationship(back_populates="deals")
 
     status_history: Mapped[list["DealStatusHistory"]] = relationship(
         back_populates="deal",