feat(tailwindcss): upgrade tailwindcss to v4

[halvaradop]

Description

This pull request upgrades TailwindCSS to the latest version, which introduces significant breaking changes—particularly in how theme variables are defined and customized. The tailwind.config.ts file has been removed, as the new version of Tailwind encourages configuration through the global CSS file of the application.

Additionally, this PR updates the CSS variables used across the packages provided by the @halvaradop/ui library. Several new variables have been introduced to better reflect the design system's standards, while unused or unnecessary variables have been removed.

Removed CSS Variables

• --primary-hover
• --secondary-hover
• --blue, --blue-hover
• --yellow, --yellow-hover
• --input-border, --input-background
• --modal
• --dialog
• --text-base
• --text-inverse
• --border-base
• --border-md

Added CSS Variables

• --on-primary
• --on-secondary
• --surface, --on-surface
• --muted
• --opacity-cursor
• --overlay

These changes reflect the transition to a more accessible, scalable, and consistent design system. Be sure to verify your components align with the updated variables to avoid visual regressions.

Checklist

• Documentation updated
• No warnings generated
• Self-review completed
• All tests added and passing

Notes