Feature: Add Task Categorization/Tagging

[Sapna700]

Description

Add support for categorizing tasks with tags/categories (e.g., Work, Personal, Shopping, Health) to help users organize and filter their tasks.

Goals

• Add tags/categories to tasks
• Filter tasks by category
• Display category in task list
• Support multiple tags per task (optional)

Implementation Details

• Add category or tags field to task structure
• Add CLI commands:
  • add <task> --category work
  • category <task_number> <category>
  • list <category> - Show tasks in category
  • categories - Show all categories

Acceptance Criteria

• ✅ Tasks can be assigned categories
• ✅ Categories display in task list
• ✅ Tasks can be filtered by category
• ✅ Multiple tags supported (optional)
• ✅ Unit tests added
• ✅ Documentation updated

Example Usage

You: add Debug login issue --category work
Task added: Debug login issue (Category: work)

You: add Buy milk --category shopping
Task added: Buy milk (Category: shopping)

You: list work
1. [work] Debug login issue
2. [work] Review pull requests

You: list shopping
1. [shopping] Buy milk
2. [shopping] Buy groceries

Related Issues

Part of TaskPilot-AI roadmap