chore(dependencies): update Tailwind CSS and related configurations

- Removed @tailwindcss/postcss from devDependencies and updated tailwindcss to version 3.4.15 for improved styling.
- Added autoprefixer as a new dependency to enhance CSS compatibility.
- Updated postcss.config.js to reflect the new Tailwind CSS plugin structure.
- Created a new tailwind.config.js file to define Tailwind's configuration.
- Adjusted CSS imports in index.css to utilize Tailwind's utility classes.
- Refined focus styles across various components for better accessibility and visual consistency.

worklenz-frontend/src/components/task-management/task-status-dropdown.tsx

@@ -185,7 +185,7 @@ const TaskStatusDropdown: React.FC<TaskStatusDropdownProps> = ({
                 >
                   {/* Status Color Indicator */}
                   <div 
-                    className={`w-3 h-3 rounded-full shadow-xs border-2 ${
+                    className={`w-3 h-3 rounded-full shadow-sm border-2 ${
                       isDarkMode ? 'border-gray-800/30' : 'border-white/20'
                     }`}
                     style={{ backgroundColor: getStatusColor(status) }}