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/index.css

@@ -1,27 +1,10 @@
-@import url('https://fonts.googleapis.com/css2?family=Inter:ital,opsz,wght@0,14..32,100..900;1,14..32,100..900&display=swap')
-layer(base);
-@import url('./styles/customOverrides.css') layer(base);
-@import url('./styles/task-management.css') layer(base);
+@import url('https://fonts.googleapis.com/css2?family=Inter:ital,opsz,wght@0,14..32,100..900;1,14..32,100..900&display=swap');
+@import url('./styles/customOverrides.css');
+@import url('./styles/task-management.css');
 
-@import 'tailwindcss';
-
-/*
-  The default border color has changed to `currentcolor` in Tailwind CSS v4,
-  so we've added these compatibility styles to make sure everything still
-  looks the same as it did with Tailwind CSS v3.
-
-  If we ever want to remove these styles, we need to add an explicit border
-  color utility to any element that depends on these defaults.
-*/
-@layer base {
-  *,
-  ::after,
-  ::before,
-  ::backdrop,
-  ::file-selector-button {
-    border-color: var(--color-gray-200, currentcolor);
-  }
-}
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
 
 .app-loading-container {
   transition: none !important;