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/organization_member.py

@@ -1,11 +1,13 @@
 """Organization member ORM model."""
+
 from __future__ import annotations
 
 from datetime import datetime
 from enum import StrEnum
 
 from pydantic import BaseModel, ConfigDict
-from sqlalchemy import DateTime, Enum as SqlEnum, ForeignKey, Integer, UniqueConstraint, func
+from sqlalchemy import DateTime, ForeignKey, Integer, UniqueConstraint, func
+from sqlalchemy import Enum as SqlEnum
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from app.models.base import Base, enum_values
@@ -39,7 +41,9 @@ class OrganizationMember(Base):
         default=OrganizationRole.MEMBER,
     )
     created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), server_default=func.now(), nullable=False
+        DateTime(timezone=True),
+        server_default=func.now(),
+        nullable=False,
     )
 
     organization = relationship("Organization", back_populates="members")