feat: sort smart search

Smart search currently returns a list of assets by their score. It would
be nice if we could instead filter assets, and then list them by date.
This is the default behaviour of other platforms.

mobile/lib/widgets/search/search_filter/sort_order_picker.dart

@@ -0,0 +1,42 @@
+import 'package:easy_localization/easy_localization.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_hooks/flutter_hooks.dart';
+import 'package:openapi/api.dart' show AssetOrder;
+
+enum _SortOption { bestMatch, newest, oldest }
+
+class SortOrderPicker extends HookWidget {
+  const SortOrderPicker({super.key, required this.onSelect, this.order});
+
+  final Function(AssetOrder?) onSelect;
+  final AssetOrder? order;
+
+  @override
+  Widget build(BuildContext context) {
+    final selected = useState<_SortOption>(switch (order) {
+      AssetOrder.desc => _SortOption.newest,
+      AssetOrder.asc => _SortOption.oldest,
+      _ => _SortOption.bestMatch,
+    });
+
+    return RadioGroup<_SortOption>(
+      onChanged: (value) {
+        if (value == null) return;
+        selected.value = value;
+        onSelect(switch (value) {
+          _SortOption.bestMatch => null,
+          _SortOption.newest => AssetOrder.desc,
+          _SortOption.oldest => AssetOrder.asc,
+        });
+      },
+      groupValue: selected.value,
+      child: Column(
+        children: [
+          RadioListTile(title: const Text('best_match').tr(), value: _SortOption.bestMatch),
+          RadioListTile(title: const Text('newest_first').tr(), value: _SortOption.newest),
+          RadioListTile(title: const Text('oldest_first').tr(), value: _SortOption.oldest),
+        ],
+      ),
+    );
+  }
+}