feat: Update category server version handling in createCategory and CategoryDialog

lib/data/note_repository.dart

@@ -58,12 +58,20 @@ class NoteRepository {
   Future<void> createCategory(Category category) async {
     debugPrint('createCategory called with: ${category.name}');
 
+    final DbCategory? existingCategory = await (
+      _database.select(_database.categories)..where((c) => c.id.equals(category.id))
+    ).getSingleOrNull();
+    final int effectiveServerVersion = math.max(
+      category.serverVersion,
+      existingCategory?.serverVersion ?? category.serverVersion,
+    );
+
     await _database.upsertCategory(
       CategoriesCompanion.insert(
         id: category.id,
         name: category.name,
         updatedAt: category.updatedAt,
-        serverVersion: const Value(0),
+        serverVersion: Value(effectiveServerVersion),
         isDeleted: const Value(false),
         isDirty: const Value(true),
         colorValue: Value<int?>(category.colorValue),

lib/screens/home_screen.dart

@@ -884,6 +884,7 @@ class _CategoryDialogState extends State<_CategoryDialog> {
       final Category newCategory = Category(
         id: widget.category?.id,
         name: name,
+        serverVersion: widget.category?.serverVersion ?? 0,
         updatedAt: DateTime.now(),
         colorValue: _selectedColor?.toARGB32(),
         iconCodePoint: _selectedIcon?.codePoint,