feat(category): add autocomplete for subcategories

lib/presentation/pages/restaurant_list/manual_restaurant_input_screen.dart

@@ -125,6 +125,9 @@ class _ManualRestaurantInputScreenState
     final categories = ref
         .watch(categoriesProvider)
         .maybeWhen(data: (list) => list, orElse: () => const <String>[]);
+    final subCategories = ref
+        .watch(subCategoriesProvider)
+        .maybeWhen(data: (list) => list, orElse: () => const <String>[]);
 
     return Scaffold(
       appBar: AppBar(
@@ -155,6 +158,7 @@ class _ManualRestaurantInputScreenState
                 longitudeController: _longitudeController,
                 onFieldChanged: _onFieldChanged,
                 categories: categories,
+                subCategories: subCategories,
               ),
               const SizedBox(height: 24),
               Row(

lib/presentation/pages/restaurant_list/widgets/add_restaurant_form.dart

@@ -16,6 +16,7 @@ class AddRestaurantForm extends StatefulWidget {
   final TextEditingController longitudeController;
   final Function(String) onFieldChanged;
   final List<String> categories;
+  final List<String> subCategories;
 
   const AddRestaurantForm({
     super.key,
@@ -31,6 +32,7 @@ class AddRestaurantForm extends StatefulWidget {
     required this.longitudeController,
     required this.onFieldChanged,
     this.categories = const <String>[],
+    this.subCategories = const <String>[],
   });
 
   @override
@@ -39,26 +41,52 @@ class AddRestaurantForm extends StatefulWidget {
 
 class _AddRestaurantFormState extends State<AddRestaurantForm> {
   late final FocusNode _categoryFocusNode;
+  late final FocusNode _subCategoryFocusNode;
   late Set<String> _availableCategories;
+  late Set<String> _availableSubCategories;
 
   @override
   void initState() {
     super.initState();
     _categoryFocusNode = FocusNode();
+    _subCategoryFocusNode = FocusNode();
     _availableCategories = {...widget.categories};
+    _availableSubCategories = {...widget.subCategories};
+    final currentCategory = widget.categoryController.text.trim();
+    if (currentCategory.isNotEmpty) {
+      _availableCategories.add(currentCategory);
+    }
+    final currentSubCategory = widget.subCategoryController.text.trim();
+    if (currentSubCategory.isNotEmpty) {
+      _availableSubCategories.add(currentSubCategory);
+    }
   }
 
   @override
   void didUpdateWidget(covariant AddRestaurantForm oldWidget) {
     super.didUpdateWidget(oldWidget);
     if (!setEquals(oldWidget.categories.toSet(), widget.categories.toSet())) {
-      _availableCategories = {..._availableCategories, ...widget.categories};
+      setState(() {
+        _availableCategories = {...widget.categories, ..._availableCategories};
+      });
+    }
+    if (!setEquals(
+      oldWidget.subCategories.toSet(),
+      widget.subCategories.toSet(),
+    )) {
+      setState(() {
+        _availableSubCategories = {
+          ...widget.subCategories,
+          ..._availableSubCategories,
+        };
+      });
     }
   }
 
   @override
   void dispose() {
     _categoryFocusNode.dispose();
+    _subCategoryFocusNode.dispose();
     super.dispose();
   }
 
@@ -95,19 +123,7 @@ class _AddRestaurantFormState extends State<AddRestaurantForm> {
             children: [
               Expanded(child: _buildCategoryField(context)),
               const SizedBox(width: 8),
-              Expanded(
-                child: TextFormField(
-                  controller: widget.subCategoryController,
-                  decoration: InputDecoration(
-                    labelText: '세부 카테고리',
-                    hintText: '예: 갈비',
-                    border: OutlineInputBorder(
-                      borderRadius: BorderRadius.circular(8),
-                    ),
-                  ),
-                  onChanged: widget.onFieldChanged,
-                ),
-              ),
+              Expanded(child: _buildSubCategoryField(context)),
             ],
           ),
           const SizedBox(height: 16),
@@ -339,4 +355,90 @@ class _AddRestaurantFormState extends State<AddRestaurantForm> {
       },
     );
   }
+
+  Widget _buildSubCategoryField(BuildContext context) {
+    return RawAutocomplete<String>(
+      textEditingController: widget.subCategoryController,
+      focusNode: _subCategoryFocusNode,
+      optionsBuilder: (TextEditingValue value) {
+        final query = value.text.trim();
+        if (query.isEmpty) {
+          return _availableSubCategories;
+        }
+
+        final lowerQuery = query.toLowerCase();
+        final matches = _availableSubCategories
+            .where((c) => c.toLowerCase().contains(lowerQuery))
+            .toList();
+
+        final hasExactMatch = _availableSubCategories.any(
+          (c) => c.toLowerCase() == lowerQuery,
+        );
+        if (!hasExactMatch && query.isNotEmpty) {
+          matches.insert(0, query);
+        }
+
+        return matches;
+      },
+      displayStringForOption: (option) => option,
+      onSelected: (option) {
+        final normalized = option.trim();
+        widget.subCategoryController.text = normalized;
+        if (normalized.isNotEmpty) {
+          setState(() {
+            _availableSubCategories.add(normalized);
+          });
+        }
+        widget.onFieldChanged(normalized);
+      },
+      fieldViewBuilder:
+          (context, textEditingController, focusNode, onFieldSubmitted) {
+            return TextFormField(
+              controller: textEditingController,
+              focusNode: focusNode,
+              decoration: InputDecoration(
+                labelText: '세부 카테고리',
+                hintText: '예: 갈비',
+                border: OutlineInputBorder(
+                  borderRadius: BorderRadius.circular(8),
+                ),
+                suffixIcon: const Icon(Icons.arrow_drop_down),
+              ),
+              onChanged: widget.onFieldChanged,
+              onFieldSubmitted: (_) => onFieldSubmitted(),
+            );
+          },
+      optionsViewBuilder: (context, onSelected, options) {
+        return Align(
+          alignment: Alignment.topLeft,
+          child: Material(
+            elevation: 4,
+            borderRadius: BorderRadius.circular(8),
+            child: ConstrainedBox(
+              constraints: const BoxConstraints(maxHeight: 220, minWidth: 200),
+              child: ListView.builder(
+                padding: EdgeInsets.zero,
+                shrinkWrap: true,
+                itemCount: options.length,
+                itemBuilder: (context, index) {
+                  final option = options.elementAt(index);
+                  final isNewEntry = !_availableSubCategories.contains(option);
+                  return ListTile(
+                    dense: true,
+                    title: Text(
+                      isNewEntry ? '새 세부 카테고리 추가: $option' : option,
+                      style: TextStyle(
+                        fontWeight: isNewEntry ? FontWeight.w600 : null,
+                      ),
+                    ),
+                    onTap: () => onSelected(option),
+                  );
+                },
+              ),
+            ),
+          ),
+        );
+      },
+    );
+  }
 }

lib/presentation/pages/restaurant_list/widgets/edit_restaurant_dialog.dart

@@ -166,6 +166,9 @@ class _EditRestaurantDialogState extends ConsumerState<EditRestaurantDialog> {
     final categories = ref
         .watch(categoriesProvider)
         .maybeWhen(data: (list) => list, orElse: () => const <String>[]);
+    final subCategories = ref
+        .watch(subCategoriesProvider)
+        .maybeWhen(data: (list) => list, orElse: () => const <String>[]);
 
     return Dialog(
       backgroundColor: isDark ? AppColors.darkSurface : AppColors.lightSurface,
@@ -197,6 +200,7 @@ class _EditRestaurantDialogState extends ConsumerState<EditRestaurantDialog> {
                 longitudeController: _longitudeController,
                 onFieldChanged: _onFieldChanged,
                 categories: categories,
+                subCategories: subCategories,
               ),
               const SizedBox(height: 24),
               Row(