fix: 修复终端统计组件字段名称错误

- 将 is_active 改为 is_online（与数据库表结构一致）
- 更新描述文本从'激活'改为'在线'

app/Filament/Widgets/TerminalStatsWidget.php

@@ -17,7 +17,7 @@ class TerminalStatsWidget extends BaseWidget
     {
         // 统计终端数据
         $totalTerminals = Terminal::count();
-        $activeTerminals = Terminal::where('is_active', true)->count();
+        $onlineTerminals = Terminal::where('is_online', true)->count();
         
         // 统计知识库关联
         $totalKnowledgeBases = TerminalKnowledgeBase::count();
@@ -36,7 +36,7 @@ class TerminalStatsWidget extends BaseWidget
 
         return [
             Stat::make('终端总数', $totalTerminals)
-                ->description("{$activeTerminals} 个激活")
+                ->description("{$onlineTerminals} 个在线")
                 ->descriptionIcon('heroicon-m-computer-desktop')
                 ->color('primary')
                 ->url(route('filament.admin.resources.terminals.index')),