feat: client endpoints fixes for client tab in deal editor

models/deal.py

@@ -1,13 +1,14 @@
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 
 from sqlalchemy import ForeignKey
-from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy.orm import Mapped, mapped_column, relationship, backref
 
 from models.base import BaseModel
 from models.mixins import SoftDeleteMixin, CreatedAtMixin, IdMixin
 
 if TYPE_CHECKING:
     from models import Status, Board, DealStatusHistory
+    from modules.clients.models import Client
 
 
 class Deal(BaseModel, IdMixin, SoftDeleteMixin, CreatedAtMixin):
@@ -33,3 +34,11 @@ class Deal(BaseModel, IdMixin, SoftDeleteMixin, CreatedAtMixin):
         cascade="all, delete-orphan",
         lazy="noload",
     )
+
+    # module client
+    client_id: Mapped[Optional[int]] = mapped_column(
+        ForeignKey("clients.id", ondelete="CASCADE"),
+    )
+    client: Mapped["Client"] = relationship(
+        backref=backref("deals", cascade="all, delete-orphan"), lazy="immediate"
+    )