feat: PTY kubectl终端 + 侧边栏对齐修复 + 构建缓存清理

**kubectl WebShell 修复：**
- 引入 github.com/creack/pty 库实现真正的伪终端
- 替换 bash --noediting + TERM=dumb 方案为 PTY-backed bash
- 支持 xterm-256color、窗口自适应、readline 交互
- 修复键盘输入无响应问题

**侧边栏优化：**
- 独立菜单项高度从 py-1.5 改为 h-8，与父菜单对齐
- 独立菜单图标从 h-3 w-3 改为 h-3.5 w-3.5，统一 14px

**构建优化：**
- run.sh docker up 增加 docker image prune -f 清理悬空镜像
- 每次部署自动清理 builder cache + dangling images

**认证修复（历史）：**
- Token 存储：Zustand + localStorage 双写，http.ts 双源 fallback
- YamlViewer/DeploymentDetail token 来源统一为 Zustand store

frontend/src/components/kubernetes/KubernetesClusters.tsx

@@ -26,11 +26,13 @@ import {
   Eye,
   Trash2,
   Search,
+  Container,
 } from 'lucide-react';
 import { kubernetesApi } from '@/services/api';
 import type { KubernetesCluster } from '@/types';
 import { KubernetesClusterDetail } from './KubernetesClusterDetail';
 import { KubernetesClusterDialog } from './KubernetesClusterDialog';
+import { KubectlTerminal } from './KubectlTerminal';
 
 export function KubernetesClusters() {
   const [clusters, setClusters] = useState<any[]>([]);
@@ -42,6 +44,10 @@ export function KubernetesClusters() {
   const [dialogOpen, setDialogOpen] = useState(false);
   const [editingCluster, setEditingCluster] = useState<any>(null);
 
+  // kubectl 终端
+  const [kubectlCluster, setKubectlCluster] = useState<{id: number; name: string} | null>(null);
+  const [kubectlTerminalOpen, setKubectlTerminalOpen] = useState(false);
+
   const loadData = async () => {
     try {
       setLoading(true);
@@ -273,6 +279,17 @@ export function KubernetesClusters() {
                             <Settings className="h-4 w-4 mr-2" />
                             配置
                           </DropdownMenuItem>
+                          <DropdownMenuItem
+                            className="text-emerald-400 focus:bg-slate-700 focus:text-emerald-300"
+                            onClick={(e) => {
+                              e.stopPropagation();
+                              setKubectlCluster({ id: cluster.id, name: cluster.name });
+                              setKubectlTerminalOpen(true);
+                            }}
+                          >
+                            <Container className="h-4 w-4 mr-2" />
+                            kubectl
+                          </DropdownMenuItem>
                           <DropdownMenuSeparator className="bg-slate-700" />
                           <DropdownMenuItem
                             className="text-red-400 focus:bg-slate-700 focus:text-red-400"
@@ -355,6 +372,19 @@ export function KubernetesClusters() {
         editingCluster={editingCluster}
         onSaved={loadData}
       />
+
+      {/* kubectl 终端 */}
+      {kubectlCluster && (
+        <KubectlTerminal
+          open={kubectlTerminalOpen}
+          onOpenChange={(open) => {
+            setKubectlTerminalOpen(open);
+            if (!open) setKubectlCluster(null);
+          }}
+          clusterId={kubectlCluster.id}
+          clusterName={kubectlCluster.name}
+        />
+      )}
     </div>
   );
 }