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/task.py

@@ -1,4 +1,5 @@
 """Task ORM model and schemas."""
+
 from __future__ import annotations
 
 from datetime import datetime
@@ -22,7 +23,9 @@ class Task(Base):
     due_date: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
     is_done: Mapped[bool] = mapped_column(Boolean, nullable=False, default=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,
     )
 
     deal = relationship("Deal", back_populates="tasks")