Feature: Add Plan History and Save Functionality with Local Storage

[PU-MEriksson]

Problem
Users currently lose their generated action plans when they:

• Refresh the page
• Navigate away from the app
• Close their browser
• Experience any interruption in their session

This creates a frustrating user experience, especially for users who spend time generating and refining detailed plans, only to lose all their work.

Current Behavior

• User generates an action plan
• Plan is displayed in the current session only
• If user navigates away or refreshes, the plan is permanently lost
• No way to access previously generated plans
• Users must regenerate plans from scratch each time

Expected Behavior

• Generated plans are automatically saved to browser's local storage
• Users can access a history of their previous plans
• Plans persist across browser sessions
• Users can revisit and reference old plans
• Optional: Users can delete plans they no longer need

Proposed Solution
Implement a plan history system using browser local storage to persist user-generated action plans across sessions.