Major frontend and admin improvements

Frontend changes:
- Removed brand filter and column from table
- Removed inventory summary grid
- Removed stanje (state) and težina (weight) columns
- Reorganized filters: Material → Finish → Color
- Updated EnhancedFilters component with new filter structure
- Removed legend section for storage conditions

Admin dashboard changes:
- Removed sidebar navigation (Boje option)
- Made dashboard full screen
- Removed brand column from table
- Removed brand field from add/edit form
- Updated all boolean columns to use checkmark/X icons
- Made color tiles 40% bigger
- Added sortable columns functionality
- Auto-fill price: 3499 for refill, 3999 for regular

Other improvements:
- Added BackToTop button component on all pages
- Fixed Next.js dialog backdrop CSS error
- Updated tests to match new UI structure
- Removed obsolete FilamentTable.tsx component
- Ensured proper synchronization between admin and frontend

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/components/ColorSwatch.tsx

@@ -16,7 +16,7 @@ export const ColorSwatch: React.FC<ColorSwatchProps> = ({
   className = ''
 }) => {
   const sizeClasses = {
-    sm: 'w-6 h-6',
+    sm: 'w-7 h-7',
     md: 'w-8 h-8',
     lg: 'w-10 h-10'
   };
@@ -63,12 +63,12 @@ export const ColorSwatch: React.FC<ColorSwatchProps> = ({
   return (
     <div className={`flex items-center gap-2 ${className}`}>
       <div 
-        className={`${sizeClasses[size]} rounded-full border-2 ${isLight ? 'border-gray-300' : 'border-gray-700'} shadow-sm`}
+        className={`${sizeClasses[size]} rounded border border-gray-300 dark:border-gray-600`}
         style={{ backgroundColor }}
         title={name}
       >
         {name.toLowerCase().includes('transparent') && (
-          <div className="w-full h-full rounded-full bg-gradient-to-br from-gray-200 to-gray-300 opacity-50" />
+          <div className="w-full h-full rounded bg-gradient-to-br from-gray-200 to-gray-300 opacity-50" />
         )}
       </div>
       {showLabel && (