Feature: Add Task Persistence (Save Tasks to File)

[Sapna700]

Description

Currently, all tasks are stored in memory and are lost when the application exits. We need to implement task persistence so that tasks are saved to a file and automatically loaded when the application starts.

Goals

• Save tasks to a JSON or pickle file
• Automatically load tasks on startup
• Preserve task data between sessions
• Handle file I/O errors gracefully

Implementation Details

• Create a TaskStorage class or module
• Add methods to TaskPilot agent:
  • save_tasks() - Save tasks to file
  • load_tasks() - Load tasks from file
  • Auto-save on every task change
• Use tasks.json or similar file format
• Add error handling for file operations

Acceptance Criteria

• ✅ Tasks persist after application closes
• ✅ Tasks load automatically on startup
• ✅ File I/O errors are handled gracefully
• ✅ Unit tests added for persistence
• ✅ README updated with persistence info

Example Usage

# Tasks are automatically saved
agent.add_task("Buy groceries")  # Saved to file

# Exit and restart app
# Tasks are automatically loaded
agent.view_tasks()  # Shows "Buy groceries"

Related Issues

Part of the TaskPilot-AI roadmap improvements