feat: 自定义仪表板，添加知识库和终端统计组件

- 创建自定义 Dashboard 页面替换默认仪表板
- 新增 KnowledgeBaseStatsWidget 显示知识库统计信息
  - 文档总数、转换完成数、转换失败数、处理中数量
  - 知识库分组数量
  - 转换成功率计算
- 新增 TerminalStatsWidget 显示终端统计信息
  - 终端总数和激活状态
  - 知识库关联数、提示词配置数
  - 今日同步成功/失败统计
- 移除默认的 FilamentInfoWidget
- 统计卡片支持点击跳转到相关管理页面

app/Filament/Widgets/TerminalStatsWidget.php

@@ -0,0 +1,65 @@
+<?php
+
+namespace App\Filament\Widgets;
+
+use App\Models\Terminal;
+use App\Models\TerminalKnowledgeBase;
+use App\Models\TerminalPrompt;
+use App\Models\TerminalSyncLog;
+use Filament\Widgets\StatsOverviewWidget as BaseWidget;
+use Filament\Widgets\StatsOverviewWidget\Stat;
+
+class TerminalStatsWidget extends BaseWidget
+{
+    protected static ?int $sort = 2;
+
+    protected function getStats(): array
+    {
+        // 统计终端数据
+        $totalTerminals = Terminal::count();
+        $activeTerminals = Terminal::where('is_active', true)->count();
+        
+        // 统计知识库关联
+        $totalKnowledgeBases = TerminalKnowledgeBase::count();
+        
+        // 统计提示词
+        $totalPrompts = TerminalPrompt::count();
+        
+        // 统计最近同步
+        $recentSyncs = TerminalSyncLog::where('created_at', '>=', now()->subDay())
+            ->where('status', 'success')
+            ->count();
+        
+        $failedSyncs = TerminalSyncLog::where('created_at', '>=', now()->subDay())
+            ->where('status', 'failed')
+            ->count();
+
+        return [
+            Stat::make('终端总数', $totalTerminals)
+                ->description("{$activeTerminals} 个激活")
+                ->descriptionIcon('heroicon-m-computer-desktop')
+                ->color('primary')
+                ->url(route('filament.admin.resources.terminals.index')),
+            
+            Stat::make('知识库关联', $totalKnowledgeBases)
+                ->description('终端知识库配置数')
+                ->descriptionIcon('heroicon-m-link')
+                ->color('info'),
+            
+            Stat::make('提示词配置', $totalPrompts)
+                ->description('终端提示词总数')
+                ->descriptionIcon('heroicon-m-chat-bubble-left-right')
+                ->color('success'),
+            
+            Stat::make('今日同步成功', $recentSyncs)
+                ->description('最近24小时')
+                ->descriptionIcon('heroicon-m-arrow-path')
+                ->color('success'),
+            
+            Stat::make('今日同步失败', $failedSyncs)
+                ->description($failedSyncs > 0 ? '需要检查' : '运行正常')
+                ->descriptionIcon($failedSyncs > 0 ? 'heroicon-m-exclamation-triangle' : 'heroicon-m-check-circle')
+                ->color($failedSyncs > 0 ? 'danger' : 'success'),
+        ];
+    }
+}