Add due_date field to Task

[Navashub]

Description

Tasks need a deadline. Add an optional due_date field so users can set when a task should be completed.

What to do

• Add a due_date column to the Task model in models.py
  • Type: DateTime, nullable, no default
• Add due_date as an optional field to TaskCreate and TaskUpdate schemas
  • Accept it as an ISO 8601 string: "2025-12-31T18:00:00"
  • Use Optional[datetime] = None
• Include due_date in the TaskResponse schema

Acceptance Criteria

• POST /tasks/ accepts an optional due_date
• GET /tasks/ returns due_date (or null if not set) for every task
• Existing tasks without a due_date still work fine

Hints

• Import datetime from Python's standard library
• In Pydantic v2, use Optional[datetime] = None
• In SQLAlchemy, use Column(DateTime, nullable=True)

Difficulty

🟢 Beginner — Good First Issue