Fix: Add missing grid styles for Yearly Contribution Heatmap

[Abhishek2005-ard]

Description

This PR resolves the distorted vertical layout issue in the Yearly Contribution Heatmap calendar by adding the necessary custom Tailwind grid utilities.

Since Tailwind CSS only generates grid-cols-* and grid-rows-* utility classes up to 12 by default, the calendar's 53x7 layout was collapsing.

Changes Made

• Added .grid-cols-53 to explicitly support the 53 weeks layout.
• Added .grid-rows-7 to support the 7 days of the week rows.
• Added .text-glow class for the heatmap hover/active states.
• Injected these custom definitions globally into frontend/src/index.css under the @layer utilities block for reusability.

Related Issue

Closes #1186 (or whichever issue number this corresponds to)

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

close #1186