feat: remove unused methods and improve widget styling in various screens

flutter/lib/features/admin/presentation/admin_aliases_panel.dart

@@ -231,7 +231,7 @@ class _AdminAliasesPanelState extends ConsumerState<AdminAliasesPanel> {
             const SizedBox(width: 8),
             Expanded(
               child: DropdownButtonFormField<int>(
-                value: _selectedProductId,
+                initialValue: _selectedProductId,
                 decoration: const InputDecoration(
                   labelText: 'Produkt',
                   border: OutlineInputBorder(),

flutter/lib/features/import/presentation/receipt_import_tab.dart

@@ -667,7 +667,7 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
       decoration: BoxDecoration(
         color: bg,
         borderRadius: BorderRadius.circular(999),
-        border: Border.all(color: fg.withOpacity(0.3)),
+        border: Border.all(color: fg.withValues(alpha: 0.3)),
       ),
       child: Text(
         label,
@@ -987,7 +987,7 @@ class _ReceiptImportResultRow extends ConsumerWidget {
                 Icon(Icons.kitchen_outlined, size: 12, color: Colors.blue.shade700),
                 const SizedBox(width: 3),
                 Text(
-                  'I lager: ${existingInv.quantity} ${existingInv.unit} → blir ${(existingInv.quantity + (convertedPreviewQty ?? 0)).toStringAsFixed(existingInv.quantity % 1 == 0 ? 0 : 2)} ${existingInv.unit}',
+                  'I lager: ${existingInv.quantity} ${existingInv.unit} → blir ${(existingInv.quantity + convertedPreviewQty!).toStringAsFixed(existingInv.quantity % 1 == 0 ? 0 : 2)} ${existingInv.unit}',
                   style: theme.textTheme.bodySmall?.copyWith(color: Colors.blue.shade700),
                 ),
               ]),

flutter/lib/features/profile/presentation/profile_screen.dart

@@ -286,7 +286,7 @@ class _ProfileScreenState extends ConsumerState<ProfileScreen> {
             MaterialPageRoute(builder: (_) => const UserAliasesScreen()),
           ),
           shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
-          tileColor: Theme.of(context).colorScheme.surfaceContainerHighest.withOpacity(0.4),
+          tileColor: Theme.of(context).colorScheme.surfaceContainerHighest.withValues(alpha: 0.4),
         ),
         const SizedBox(height: 24),
         SizedBox(

flutter/lib/features/profile/presentation/user_aliases_screen.dart

@@ -2,8 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../admin/data/admin_repository.dart';
-import '../../admin/domain/receipt_alias.dart';
-import '../../auth/data/auth_providers.dart';
+import '../../admin/domain/receipt_alias.dart';}
 
 class UserAliasesScreen extends ConsumerStatefulWidget {
   const UserAliasesScreen({super.key});