Related Issue

Closes #443

Summary

Implemented persistent view state so the selected sidebar section remains active after refreshing the page.

Changes Made

• Added localStorage support to save the current active view.
• Created a centralized applyView() function to handle view switching logic.
• Refactored duplicated sidebar view code into a reusable function.
• Restored the previously selected view automatically on page reload.
• Added validation fallback to default to calendar if stored view is invalid.

Testing

• Ran the project locally using npm start.
• Verified that Calendar, All Tasks, Archived, and Focus views persist correctly after refresh.
• Confirmed sidebar active states update properly across all views.
• Checked that no existing functionality was broken after refactoring.

Checklist

• Code follows project style
• Tested locally
• No unrelated changes included
• Documentation updated (if applicable)