refactor: 移除 AppBar 刷新按钮，统一使用下拉刷新

6 个页面（仪表盘、服务器、任务、告警、审批、常驻指令）
删除右上角 IconButton(Icons.refresh)，保留已有的 RefreshIndicator 下拉刷新。
Terminal 页面的刷新按钮是"重新连接"功能，保持不变。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

it0_app/lib/features/alerts/presentation/pages/alerts_page.dart

@@ -62,12 +62,6 @@ class _AlertsPageState extends ConsumerState<AlertsPage> {
     return Scaffold(
       appBar: AppBar(
         title: const Text('告警中心'),
-        actions: [
-          IconButton(
-            icon: const Icon(Icons.refresh),
-            onPressed: () => ref.invalidate(alertEventsProvider),
-          ),
-        ],
       ),
       body: RefreshIndicator(
         onRefresh: () async => ref.invalidate(alertEventsProvider),

it0_app/lib/features/approvals/presentation/pages/approvals_page.dart

@@ -80,12 +80,6 @@ class _ApprovalsPageState extends ConsumerState<ApprovalsPage> {
     return Scaffold(
       appBar: AppBar(
         title: const Text('审批中心'),
-        actions: [
-          IconButton(
-            icon: const Icon(Icons.refresh),
-            onPressed: () => ref.invalidate(approvalsProvider),
-          ),
-        ],
       ),
       body: Column(
         children: [

it0_app/lib/features/dashboard/presentation/pages/dashboard_page.dart

@@ -139,16 +139,6 @@ class DashboardPage extends ConsumerWidget {
     return Scaffold(
       appBar: AppBar(
         title: const Text('仪表盘'),
-        actions: [
-          IconButton(
-            icon: const Icon(Icons.refresh),
-            onPressed: () {
-              ref.invalidate(serverSummaryProvider);
-              ref.invalidate(alertSummaryProvider);
-              ref.invalidate(recentOpsProvider);
-            },
-          ),
-        ],
       ),
       body: RefreshIndicator(
         onRefresh: () async {

it0_app/lib/features/servers/presentation/pages/servers_page.dart

@@ -49,12 +49,6 @@ class _ServersPageState extends ConsumerState<ServersPage> {
     return Scaffold(
       appBar: AppBar(
         title: const Text('服务器'),
-        actions: [
-          IconButton(
-            icon: const Icon(Icons.refresh),
-            onPressed: () => ref.invalidate(serversProvider),
-          ),
-        ],
       ),
       body: RefreshIndicator(
         onRefresh: () async => ref.invalidate(serversProvider),

it0_app/lib/features/standing_orders/presentation/pages/standing_orders_page.dart

@@ -42,12 +42,6 @@ class StandingOrdersPage extends ConsumerWidget {
     return Scaffold(
       appBar: AppBar(
         title: const Text('常驻指令'),
-        actions: [
-          IconButton(
-            icon: const Icon(Icons.refresh),
-            onPressed: () => ref.invalidate(standingOrdersProvider),
-          ),
-        ],
       ),
       body: RefreshIndicator(
         onRefresh: () async => ref.invalidate(standingOrdersProvider),

it0_app/lib/features/tasks/presentation/pages/tasks_page.dart

@@ -55,12 +55,6 @@ class TasksPage extends ConsumerWidget {
     return Scaffold(
       appBar: AppBar(
         title: const Text('运维任务'),
-        actions: [
-          IconButton(
-            icon: const Icon(Icons.refresh),
-            onPressed: () => ref.invalidate(tasksProvider),
-          ),
-        ],
       ),
       body: RefreshIndicator(
         onRefresh: () async => ref.invalidate(tasksProvider),