feat: add calendar view and refine task modal UI

[Prakshil]

📌 Description

This PR addresses UI/UX inconsistencies in the Task Management module and adds a much-needed monthly calendar visualization feature. It modernizes the task interface with glassmorphism effects, improves visual hierarchy, and introduces fluid animations for a more polished user experience.

🔗 Related Issue

Closes #357

🛠 Changes Made

• Task Calendar: Created a new TaskCalendar component to visualize tasks on a monthly grid with color-coded priority pills.
• View Toggle: Implemented a stateful toggle switch in Tasks.jsx to seamlessly swap between List and Calendar views.
• Modal UI Redesign: Upgraded TaskFormModal with glassmorphism (blurred backdrop, translucent background) and framer-motion spring animations.
• Task Item Polish: Improved spacing and alignment in TaskItem, added hover-lift animations, and updated priority badges to use filled color styles rather than just borders.
• Animation Support: Wrapped conditionally rendered components in AnimatePresence to enable smooth layout transitions and exit animations.

📸 Screenshots (if applicable)

The Create Task Modal

The Calendar in the Tasks Section

✅ Checklist

• Code runs locally
• Followed project structure
• No console errors
• Properly tested changes
• Linked the issue

🚀 Notes for Reviewers

• The TaskFormModal was intentionally moved outside of the main animated container in Tasks.jsx to ensure the modal's fixed backdrop successfully covers the entire viewport.
• The frontend has successfully passed the npm run lint and npm run build checks with zero errors.

[Prakshil]

Please review and merge this @AdityaSekharDas . Thank you.