fix: 清理 unused-vars 回归(32→0) + 修复 go:embed 编译阻塞

1. ESLint unused-vars 从 32 清零（回归修复）
   - 删除 14 个文件中未使用的 import（lucide 图标/shadcn 组件/JsonData 类型）
   - 移除未使用的变量/参数（categoryLabels/updateEntry/onSaved 等）
   - 涉及: AppRelease/PipelineEditor/KubernetesNodes/AlertCenter/SilenceRulesPanel 等

2. 修复 go:embed all:static 编译阻塞
   - 新增 backend/static/.gitkeep 占位文件
   - 全新 clone 后 go build ./... 可直接通过（不再依赖先 npm run build）

3. 安装缺失的 npm 依赖
   - react-markdown/remark-gfm（AgentMarkdown 组件）
   - @codemirror/lang-python/@codemirror/legacy-modes（ScriptCodeEditor 组件）

验证: go build✅ | tsc -b✅ | npm build✅(21s) | ESLint any=41 unused=0 | 17/17 集成测试✅

frontend/src/pages/approval/ApprovalWorkflowPage.tsx

@@ -210,12 +210,6 @@ function WorkflowEditorModal({ workflow, users, onClose, onSaved }: EditorProps)
   const [submitting, setSubmitting] = useState(false);
   const [error, setError] = useState('');
 
-  const categoryLabels: Record<string, string> = {
-    resource: t('approval.category.resource'),
-    app: t('approval.category.app'),
-    permission: t('approval.category.permission'),
-  };
-
   const stepTypeLabels: Record<string, string> = {
     submit: t('approval.step.submit'),
     audit: t('approval.step.audit'),

frontend/src/pages/audit/AuditOperationsTab.tsx

@@ -4,7 +4,6 @@ import { useState, useEffect, useCallback, useMemo, useRef } from 'react';
 import { cn } from '@/lib/utils';
 import { useTranslation } from 'react-i18next';
 import { useVirtualizer } from '@tanstack/react-virtual';
-import { Card, CardContent } from '@/components/ui/card';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
 import { Badge } from '@/components/ui/badge';

frontend/src/pages/monitor/host-monitor/ZoomableAreaChart.tsx

@@ -64,7 +64,6 @@ function ChartBody({
   unit,
   yDomain,
   gradPrefix,
-  zoomRange,
   refLeft,
   refRight,
   onMouseDown,

frontend/src/pages/monitor/host-monitor/utils.ts

@@ -168,7 +168,7 @@ export function buildMetricsFromHistory(history: JsonData[], timeConfig: TimeCon
 }
 
 /** 从过滤后历史计算实际数据时间跨度（用于展示） // Logan.Li */
-export function getActualDataSpan(history: JsonData[], range: HostMonitorTimeRange): string | null {
+export function getActualDataSpan(history: JsonData[], _range: HostMonitorTimeRange): string | null {
   if (!history.length) return null;
   const ts = history.map(recordTimestamp).filter((t) => t > 0);
   if (!ts.length) return null;