fix: 仪表盘概览卡片等高对齐

- Row 外层包 IntrinsicHeight + CrossAxisAlignment.stretch，三卡自动等高
- Loading/Error 卡片去掉固定 height:140，改为 padding + stretch 拉伸

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

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

@@ -165,18 +165,18 @@ class DashboardPage extends ConsumerWidget {
               style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold),
             ),
             const SizedBox(height: 12),
-            Row(
+            IntrinsicHeight(
+              child: Row(
+                crossAxisAlignment: CrossAxisAlignment.stretch,
                 children: [
-                // Server card
                   Expanded(child: _buildServerCard(serverAsync)),
                   const SizedBox(width: 12),
-                // Alert card
                   Expanded(child: _buildAlertCard(alertAsync)),
                   const SizedBox(width: 12),
-                // Tasks card
                   Expanded(child: _buildTasksCard(recentOpsAsync)),
                 ],
               ),
+            ),
             const SizedBox(height: 24),
             // ------------- Recent operations --------------------------------
             const Text(
@@ -399,8 +399,8 @@ class _SummaryCardLoading extends StatelessWidget {
   Widget build(BuildContext context) {
     return const Card(
       color: AppColors.surface,
-      child: SizedBox(
-        height: 140,
+      child: Padding(
+        padding: EdgeInsets.all(14),
         child: Center(child: CircularProgressIndicator(strokeWidth: 2)),
       ),
     );
@@ -415,11 +415,8 @@ class _SummaryCardError extends StatelessWidget {
   Widget build(BuildContext context) {
     return Card(
       color: AppColors.surface,
-      child: SizedBox(
-        height: 140,
-        child: Center(
       child: Padding(
-            padding: const EdgeInsets.all(12),
+        padding: const EdgeInsets.all(14),
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,
           children: [
@@ -435,8 +432,6 @@ class _SummaryCardError extends StatelessWidget {
           ],
         ),
       ),
-        ),
-      ),
     );
   }
 }