refactor: update class names for consistency and improve styling

- Changed `flex-shrink-0` to `shrink-0` in multiple components for better consistency.
- Updated button and checkbox classes to use `rounded-sm` for a more uniform appearance.
- Adjusted backdrop blur classes for modals to `backdrop-blur-xs` for a subtler effect.
- Removed unused Tailwind CSS configuration file.

src/components/Sidebar.jsx

@@ -43,7 +43,7 @@ export default function Sidebar({ open, onClose }) {
 
   const linkClasses = ({ isActive }) =>
     `flex items-center gap-3 px-3 py-2.5 rounded-lg text-sm font-medium transition-all duration-200 ${isActive
-      ? 'bg-th-accent text-th-accent-t shadow-sm'
+      ? 'bg-th-accent text-th-accent-t shadow-xs'
       : 'text-th-text-s hover:text-th-text hover:bg-th-hover'
     }`;
 
@@ -106,7 +106,7 @@ export default function Sidebar({ open, onClose }) {
           <div className="p-4 border-t border-th-border">
             <div className="flex items-center gap-3">
               <div
-                className="w-9 h-9 rounded-full flex items-center justify-center text-white text-sm font-bold flex-shrink-0 overflow-hidden"
+                className="w-9 h-9 rounded-full flex items-center justify-center text-white text-sm font-bold shrink-0 overflow-hidden"
                 style={{ backgroundColor: user?.avatar_color || '#6366f1' }}
               >
                 {user?.avatar_image ? (