Refactor code for improved readability and consistency

- Reformatted function signatures in `organization_service.py` and `task_service.py` for better alignment.
- Updated import statements across multiple files for consistency and organization.
- Enhanced test files by improving formatting and ensuring consistent use of async session factories.
- Added type hints and improved type safety in various service and test files.
- Adjusted `pyproject.toml` to include configuration for isort, mypy, and ruff for better code quality checks.
- Cleaned up unused imports and organized existing ones in several test files.

app/models/user.py

@@ -1,4 +1,5 @@
 """User ORM model and Pydantic schemas."""
+
 from __future__ import annotations
 
 from datetime import datetime
@@ -25,13 +26,20 @@ class User(Base):
     name: Mapped[str] = mapped_column(String(255), nullable=False)
     is_active: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)
     created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), server_default=func.now(), nullable=False
+        DateTime(timezone=True),
+        server_default=func.now(),
+        nullable=False,
     )
     updated_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False
+        DateTime(timezone=True),
+        server_default=func.now(),
+        onupdate=func.now(),
+        nullable=False,
     )
 
-    memberships = relationship("OrganizationMember", back_populates="user", cascade="all, delete-orphan")
+    memberships = relationship(
+        "OrganizationMember", back_populates="user", cascade="all, delete-orphan"
+    )
     owned_contacts = relationship("Contact", back_populates="owner")
     owned_deals = relationship("Deal", back_populates="owner")
     activities = relationship("Activity", back_populates="author")