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.py

@@ -1,4 +1,5 @@
 """Organization ORM model and schemas."""
+
 from __future__ import annotations
 
 from datetime import datetime
@@ -18,7 +19,9 @@ class Organization(Base):
     id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
     name: Mapped[str] = mapped_column(String(255), nullable=False, unique=True)
     created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), server_default=func.now(), nullable=False
+        DateTime(timezone=True),
+        server_default=func.now(),
+        nullable=False,
     )
 
     members = relationship(