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>

app/upadaj/colors/page.tsx

@@ -250,14 +250,20 @@ export default function ColorsManagement() {
                         <button
                           onClick={() => setEditingColor(color)}
                           className="text-blue-600 dark:text-blue-400 hover:text-blue-900 dark:hover:text-blue-300 mr-3"
+                          title="Izmeni"
                         >
-                          Izmeni
+                          <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                            <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M11 5H6a2 2 0 00-2 2v11a2 2 0 002 2h11a2 2 0 002-2v-5m-1.414-9.414a2 2 0 112.828 2.828L11.828 15H9v-2.828l8.586-8.586z" />
+                          </svg>
                         </button>
                         <button
                           onClick={() => handleDelete(color.id)}
                           className="text-red-600 dark:text-red-400 hover:text-red-900 dark:hover:text-red-300"
+                          title="Obriši"
                         >
-                          Obriši
+                          <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                            <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M19 7l-.867 12.142A2 2 0 0116.138 21H7.862a2 2 0 01-1.995-1.858L5 7m5 4v6m4-6v6m1-10V4a1 1 0 00-1-1h-4a1 1 0 00-1 1v3M4 7h16" />
+                          </svg>
                         </button>
                       </td>
                     </tr>