feat: refactor theme, add tailwind-scrollbar, and improve UI components

- Removed manual theme switching logic and ThemeProvider
- Installed and configured tailwind-scrollbar plugin
- Updated FileConverter and ConversionOptions to use shadcn Input
- Refactored FontSelector to use shadcn Tabs
- Simplified global styles and adjusted glassmorphic effects

components/layout/AppSidebar.tsx

@@ -5,11 +5,6 @@ import Link from 'next/link';
 import { usePathname } from 'next/navigation';
 import { 
   ChevronRight,
-  MousePointer2, 
-  Palette, 
-  Eye, 
-  Languages, 
-  Layers,
   ChevronLeft,
   X
 } from 'lucide-react';
@@ -73,13 +68,13 @@ export function AppSidebar() {
       {/* Mobile Overlay Backdrop */}
       {isOpen && (
         <div 
-          className="fixed inset-0 bg-background/80 backdrop-blur-sm z-40 lg:hidden"
+          className="fixed inset-0 bg-transparent backdrop-blur-sm z-40 lg:hidden"
           onClick={close}
         />
       )}
 
       <aside className={cn(
-        "fixed inset-y-0 left-0 z-50 flex flex-col border-r border-border bg-background/40 backdrop-blur-2xl transition-all duration-300 ease-in-out lg:relative lg:h-full",
+        "fixed inset-y-0 left-0 z-50 flex flex-col border-r border-border bg-background/10 backdrop-blur-2xl transition-all duration-300 ease-in-out lg:relative lg:h-full",
         isOpen ? "translate-x-0" : "-translate-x-full lg:translate-x-0",
         isCollapsed ? "lg:w-20" : "w-64"
       )}>
@@ -106,7 +101,7 @@ export function AppSidebar() {
         </div>
 
         {/* Navigation */}
-        <nav className="flex-1 overflow-y-auto px-4 py-2 space-y-8 mt-4 scrollbar-hide">
+        <nav className="flex-1 overflow-y-auto px-4 py-2 space-y-8 mt-4 overflow-x-hidden">
           {navigation.map((group) => (
             <div key={group.label} className="space-y-2">
               {!isCollapsed && (