Add color request feature with modal and Safari styling fixes

- Implement color request modal popup instead of separate page
- Add Serbian translations throughout
- Fix Safari form styling issues with custom CSS
- Add 'Other' option to material and finish dropdowns
- Create admin panel for managing color requests
- Add database migration for color_requests table
- Implement API endpoints for color request management

app/upadaj/dashboard/page.tsx

@@ -377,6 +377,18 @@ export default function AdminDashboard() {
                     selectedFilaments={selectedFilaments}
                     onSaleUpdate={fetchFilaments}
                   />
+                  <button
+                    onClick={() => router.push('/upadaj/colors')}
+                    className="flex-1 sm:flex-initial px-3 sm:px-4 py-2 bg-purple-500 text-white rounded hover:bg-purple-600 text-sm sm:text-base"
+                  >
+                    Boje
+                  </button>
+                  <button
+                    onClick={() => router.push('/upadaj/requests')}
+                    className="flex-1 sm:flex-initial px-3 sm:px-4 py-2 bg-indigo-500 text-white rounded hover:bg-indigo-600 text-sm sm:text-base"
+                  >
+                    Zahtevi
+                  </button>
                   <button
                     onClick={() => router.push('/')}
                     className="flex-1 sm:flex-initial px-3 sm:px-4 py-2 bg-blue-500 text-white rounded hover:bg-blue-600 text-sm sm:text-base"