Enhancement: Smooth navbar toggle and improved hover transitions

[Nilam-Kumari-Mahato]

🔧 Enhancement Summary:

• Implemented a smooth transition effect for the navbar toggle on smaller screens.
• Replaced abrupt show/hide behavior with max-height, opacity, and transform transitions.
• Improved hover effects on navbar items using scaling, gradient background, and shadow transitions.
• Resolved the previous flickering/jumpy animation issue during toggle and hover.
• Ensured clean and responsive behavior on various screen sizes.

🎥 Updated behavior demo:
Click here to view screen recording

Closes #433

[greptile-apps]

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