optimization: desktop UI (#747)

lib/view/page/server/tab/top_bar.dart

@@ -0,0 +1,62 @@
+part of 'tab.dart';
+
+final class _TopBar extends StatelessWidget implements PreferredSizeWidget {
+  final ValueNotifier<Set<String>> tags;
+  final void Function(String) onTagChanged;
+  final String initTag;
+
+  const _TopBar({
+    required this.initTag,
+    required this.onTagChanged,
+    required this.tags,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    final isMobile = ResponsiveBreakpoints.of(context).isMobile;
+    if (!isMobile) return UIs.placeholder;
+
+    return Padding(
+      padding: const EdgeInsets.only(left: 10),
+      child: Row(
+        mainAxisAlignment: MainAxisAlignment.spaceBetween,
+        children: [
+          // Keep this btn. For issue #657.
+          InkWell(
+            borderRadius: BorderRadius.circular(13),
+            onTap: () {
+              SettingsPage.route.go(context);
+            },
+            child: const Padding(
+              padding: EdgeInsets.symmetric(horizontal: 7, vertical: 3),
+              child: Row(
+                children: [
+                  Text(
+                    BuildData.name,
+                    style: TextStyle(fontSize: 19),
+                  ),
+                  SizedBox(width: 5),
+                  Icon(
+                    Icons.settings,
+                    size: 17,
+                  ),
+                ],
+              ),
+            ),
+          ),
+          const SizedBox(width: 30),
+          TagSwitcher(
+            tags: tags,
+            onTagChanged: onTagChanged,
+            initTag: initTag,
+            singleLine: true,
+            reversed: true,
+          ).expanded(),
+        ],
+      ),
+    );
+  }
+
+  @override
+  Size get preferredSize => const Size.fromHeight(TagSwitcher.kTagBtnHeight);
+}