feat: add HelpText model, service, and controller for dynamic help text management

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

@@ -14,6 +14,7 @@ import '../../pantry/data/pantry_providers.dart';
 import '../../pantry/domain/pantry_item.dart';
 import '../data/import_providers.dart';
 import '../data/receipt_import_session.dart';
+import '../domain/help_text_content.dart';
 import '../domain/parsed_receipt_item.dart';
 import '../../../core/ui/product_picker_field.dart' show ProductOption;
 import '../utils/receipt_import_utils.dart';
@@ -37,6 +38,7 @@ class ReceiptImportTab extends ConsumerStatefulWidget {
 class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
   bool _isLoading = false;
   bool _isSaving = false;
+  bool _isHelpLoading = false;
   PlatformFile? _pickedFile;
   bool _categoryLoadFailed = false;
   bool _globalProductsLoadFailed = false;
@@ -460,6 +462,64 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
     );
   }
 
+  Future<void> _showHelpForReceiptImport() async {
+    if (_isHelpLoading) return;
+    setState(() => _isHelpLoading = true);
+    try {
+      final token = await ref.read(authStateProvider.future);
+      final repo = ref.read(importRepositoryProvider);
+      final help = await repo.fetchHelpTextByKey('receipt_import', token: token);
+      if (!mounted) return;
+      await _showHelpDialog(help);
+    } catch (e) {
+      if (!mounted) return;
+      showGlobalErrorDialog(context, 'Kunde inte läsa hjälptexten just nu: $e');
+    } finally {
+      if (mounted) setState(() => _isHelpLoading = false);
+    }
+  }
+
+  Future<void> _showHelpDialog(HelpTextContent help) {
+    final updatedAt = help.updatedAt;
+    final updatedAtText = updatedAt == null
+        ? null
+        : '${updatedAt.year.toString().padLeft(4, '0')}-${updatedAt.month.toString().padLeft(2, '0')}-${updatedAt.day.toString().padLeft(2, '0')}';
+
+    return showDialog<void>(
+      context: context,
+      builder: (ctx) => AlertDialog(
+        title: Text(help.title.isEmpty ? 'Hjälp: Kvittoimport' : help.title),
+        content: SizedBox(
+          width: 560,
+          child: SingleChildScrollView(
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              mainAxisSize: MainAxisSize.min,
+              children: [
+                SelectableText(help.content),
+                const SizedBox(height: 12),
+                Wrap(
+                  spacing: 8,
+                  runSpacing: 8,
+                  children: [
+                    Chip(label: Text('Scope: ${help.scope}')),
+                    if (updatedAtText != null) Chip(label: Text('Uppdaterad: $updatedAtText')),
+                  ],
+                ),
+              ],
+            ),
+          ),
+        ),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.of(ctx).pop(),
+            child: const Text('Stäng'),
+          ),
+        ],
+      ),
+    );
+  }
+
   void _deleteItem(int index) {
     final items = _items;
     if (items == null || index < 0 || index >= items.length) return;
@@ -819,9 +879,28 @@ class _ReceiptImportTabState extends ConsumerState<ReceiptImportTab> {
       child: Column(
         crossAxisAlignment: CrossAxisAlignment.start,
         children: [
-          Text(
-            'Ladda upp ett kvitto (PDF eller bild) — raderna tolkas och kan läggas till i ditt inventarie.',
-            style: theme.textTheme.bodyMedium?.copyWith(color: theme.colorScheme.onSurfaceVariant),
+          Row(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              Expanded(
+                child: Text(
+                  'Ladda upp ett kvitto (PDF eller bild) — raderna tolkas och kan läggas till i ditt inventarie.',
+                  style: theme.textTheme.bodyMedium?.copyWith(color: theme.colorScheme.onSurfaceVariant),
+                ),
+              ),
+              const SizedBox(width: 8),
+              TextButton.icon(
+                onPressed: _isHelpLoading ? null : _showHelpForReceiptImport,
+                icon: _isHelpLoading
+                    ? const SizedBox(
+                        width: 14,
+                        height: 14,
+                        child: CircularProgressIndicator(strokeWidth: 2),
+                      )
+                    : const Icon(Icons.help_outline),
+                label: const Text('Läs hjälp'),
+              ),
+            ],
           ),
           const SizedBox(height: 20),
           OutlinedButton.icon(