✨ feat(explain-ui): 新增慢 SQL 历史面板与 Ctrl+Shift+H 快捷键

- 面板组件：SlowQueryPanel 含 TopN 列表 + 耗时/扫描行数/时间三种排序 + 清空操作
- 入口接入：QueryEditor 加 Ctrl+Shift+H 快捷键，点击条目回填 SQL 到编辑器
- Wails 绑定：手动同步 GetSlowQueries 与 ClearSlowQueries 到 App.js/App.d.ts
- 颜色提示：耗时 >5s 红色、>1s 橙色，便于一眼识别重查询

frontend/src/components/QueryEditor.tsx

@@ -33,6 +33,8 @@ import { SIDEBAR_SQL_EDITOR_DRAG_MIME, decodeSidebarSqlEditorDragPayload, hasSid
 import { resolveUniqueKeyGroupsFromIndexes } from './dataGridCopyInsert';
 // SQL 诊断工作台：lazy 加载避免 reactflow/dagre 进入主 bundle（约 130KB gzipped 独立 chunk）
 const ExplainWorkbench = lazy(() => import('./explain/ExplainWorkbench'));
+// 慢 SQL 历史面板：lazy 加载
+const SlowQueryPanel = lazy(() => import('./explain/SlowQueryPanel'));
 import { SUPPORTED_LANGUAGES, t as translate } from '../i18n';
 import {
     DUCKDB_ROWID_LOCATOR_COLUMN,
@@ -2211,6 +2213,8 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
 
   // SQL 诊断工作台：Ctrl+Shift+D 触发（Mac 为 Cmd+Shift+D）
   const [explainOpen, setExplainOpen] = useState(false);
+  // 慢 SQL 历史：Ctrl+Shift+H 触发
+  const [slowQueryOpen, setSlowQueryOpen] = useState(false);
 
   // Database Selection
   const [currentConnectionId, setCurrentConnectionId] = useState<string>(tab.connectionId);
@@ -2274,9 +2278,14 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
   useEffect(() => {
     if (!isActive) return;
     const handler = (e: KeyboardEvent) => {
-      if ((e.ctrlKey || e.metaKey) && e.shiftKey && (e.key === 'D' || e.key === 'd')) {
+      if (!(e.ctrlKey || e.metaKey) || !e.shiftKey) return;
+      const key = e.key.toLowerCase();
+      if (key === 'd') {
         e.preventDefault();
         setExplainOpen(true);
+      } else if (key === 'h') {
+        e.preventDefault();
+        setSlowQueryOpen(true);
       }
     };
     window.addEventListener('keydown', handler);
@@ -6157,6 +6166,19 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
           />
         )}
       </Suspense>
+
+      {/* 慢 SQL 历史：Ctrl+Shift+H 触发 */}
+      <Suspense fallback={null}>
+        {slowQueryOpen && explainConfig && (
+          <SlowQueryPanel
+            open={slowQueryOpen}
+            onClose={() => setSlowQueryOpen(false)}
+            config={explainConfig}
+            dbName={currentDb}
+            onPickQuery={(sql) => setQuery(sql)}
+          />
+        )}
+      </Suspense>
     </div>
     );
 };

frontend/src/components/explain/SlowQueryPanel.tsx

@@ -0,0 +1,222 @@
+import { useCallback, useEffect, useMemo, useState } from 'react'
+import { Button, Empty, Modal, Segmented, Spin, Tooltip, Typography, message } from 'antd'
+import { ReloadOutlined, DeleteOutlined, ThunderboltOutlined } from '@ant-design/icons'
+import { ClearSlowQueries, GetSlowQueries } from '../../../wailsjs/go/app/App'
+import { buildRpcConnectionConfig } from '../../utils/connectionRpcConfig'
+import type { ConnectionConfig } from '../../types'
+import { formatMs, formatNumber } from '../../utils/explainTypes'
+
+// 慢 SQL 历史面板。
+// 从 GetSlowQueries 加载 TopN，按 duration / rowsRead / recent 切换排序。
+// 点击条目可触发 onPickQuery 把 SQL 回填到 QueryEditor。
+//
+// 设计要点：
+//   - 独立 Modal，不依赖 Sidebar 内部布局（Sidebar.tsx 已经 9000+ 行，避免污染）
+//   - 用户从 Sidebar 一个独立按钮触发
+//   - SQL 指纹去重由后端完成，前端只展示
+
+const { Title, Text, Paragraph } = Typography
+
+type SortBy = 'duration' | 'rowsRead' | 'recent'
+
+interface SlowQueryRecord {
+  id?: string
+  connectionFp?: string
+  sqlFp?: string
+  sqlPreview?: string
+  dbType?: string
+  durationMs?: number
+  rowsRead?: number
+  rowsReturned?: number
+  planHash?: string
+  executedAt?: string
+}
+
+interface SlowQueryPanelProps {
+  open: boolean
+  onClose: () => void
+  config: ConnectionConfig
+  dbName: string
+  onPickQuery?: (sql: string) => void
+}
+
+export default function SlowQueryPanel({ open, onClose, config, dbName, onPickQuery }: SlowQueryPanelProps) {
+  const [loading, setLoading] = useState(false)
+  const [records, setRecords] = useState<SlowQueryRecord[]>([])
+  const [error, setError] = useState<string | null>(null)
+  const [sortBy, setSortBy] = useState<SortBy>('duration')
+
+  const reload = useCallback(async () => {
+    setLoading(true)
+    setError(null)
+    try {
+      const result = await GetSlowQueries(buildRpcConnectionConfig(config), dbName, sortBy, 100)
+      if (!result.success) {
+        setError(result.message || '加载失败')
+        setRecords([])
+      } else {
+        setRecords((result.data as SlowQueryRecord[]) ?? [])
+      }
+    } catch (e) {
+      setError(String(e))
+    } finally {
+      setLoading(false)
+    }
+  }, [config, dbName, sortBy])
+
+  useEffect(() => {
+    if (open) {
+      void reload()
+    }
+  }, [open, reload])
+
+  const handleClear = useCallback(async () => {
+    const result = await ClearSlowQueries(buildRpcConnectionConfig(config), dbName)
+    if (result.success) {
+      message.success('已清空慢查询历史')
+      setRecords([])
+    } else {
+      message.error(result.message || '清空失败')
+    }
+  }, [config, dbName])
+
+  const handlePick = useCallback(
+    (record: SlowQueryRecord) => {
+      if (record.sqlPreview && onPickQuery) {
+        onPickQuery(record.sqlPreview)
+        onClose()
+      }
+    },
+    [onPickQuery, onClose],
+  )
+
+  const sorted = useMemo(() => records, [records]) // 后端已排序，前端不再排
+
+  return (
+    <Modal
+      open={open}
+      onCancel={onClose}
+      footer={null}
+      width="70%"
+      style={{ top: 40 }}
+      title={
+        <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
+          <ThunderboltOutlined style={{ color: '#fa5252' }} />
+          <Title level={5} style={{ margin: 0 }}>慢 SQL 历史</Title>
+          <Text type="secondary" style={{ fontSize: 12 }}>
+            {dbName || '(当前连接)'}
+          </Text>
+        </div>
+      }
+      destroyOnClose
+    >
+      <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginBottom: 12 }}>
+        <Segmented
+          value={sortBy}
+          onChange={(v) => setSortBy(v as SortBy)}
+          options={[
+            { label: '按耗时', value: 'duration' },
+            { label: '按扫描行数', value: 'rowsRead' },
+            { label: '按时间', value: 'recent' },
+          ]}
+        />
+        <div style={{ display: 'flex', gap: 8 }}>
+          <Tooltip title="刷新">
+            <Button icon={<ReloadOutlined />} onClick={() => void reload()} loading={loading} />
+          </Tooltip>
+          <Tooltip title="清空当前连接的历史">
+            <Button danger icon={<DeleteOutlined />} onClick={() => void handleClear()} disabled={records.length === 0} />
+          </Tooltip>
+        </div>
+      </div>
+
+      {loading && (
+        <div style={{ textAlign: 'center', padding: '40px 0' }}>
+          <Spin tip="加载慢查询历史..." />
+        </div>
+      )}
+
+      {error && (
+        <Paragraph type="danger" style={{ padding: 16 }}>
+          <Text strong>加载失败：</Text>
+          {error}
+        </Paragraph>
+      )}
+
+      {!loading && !error && sorted.length === 0 && (
+        <Empty description="暂无慢查询记录（阈值 500ms）" style={{ padding: '40px 0' }} />
+      )}
+
+      {!loading && !error && sorted.length > 0 && (
+        <div style={{ display: 'flex', flexDirection: 'column', gap: 8, maxHeight: '60vh', overflowY: 'auto' }}>
+          {sorted.map((r, idx) => (
+            <SlowQueryCard key={r.id ?? idx} record={r} onPick={() => handlePick(r)} />
+          ))}
+        </div>
+      )}
+    </Modal>
+  )
+}
+
+function SlowQueryCard({ record, onPick }: { record: SlowQueryRecord; onPick: () => void }) {
+  const duration = record.durationMs ?? 0
+  const durationColor = duration >= 5000 ? '#fa5252' : duration >= 1000 ? '#f08c00' : '#495057'
+
+  return (
+    <div
+      onClick={onPick}
+      style={{
+        border: '1px solid var(--gn-border, #dee2e6)',
+        borderRadius: 4,
+        padding: 10,
+        background: 'var(--gn-card-bg, #f8f9fa)',
+        cursor: 'pointer',
+        fontSize: 12,
+      }}
+    >
+      <div style={{ display: 'flex', justifyContent: 'space-between', marginBottom: 6 }}>
+        <div style={{ display: 'flex', gap: 12, alignItems: 'center' }}>
+          <span style={{ color: durationColor, fontWeight: 600 }}>{formatMs(duration)}</span>
+          {record.rowsRead !== undefined && record.rowsRead > 0 && (
+            <span style={{ color: 'var(--gn-text-muted, #6c757d)' }}>
+              扫描 <strong>{formatNumber(record.rowsRead)}</strong>
+            </span>
+          )}
+          {record.rowsReturned !== undefined && record.rowsReturned > 0 && (
+            <span style={{ color: 'var(--gn-text-muted, #6c757d)' }}>
+              返回 <strong>{formatNumber(record.rowsReturned)}</strong>
+            </span>
+          )}
+        </div>
+        <div style={{ color: 'var(--gn-text-muted, #6c757d)' }}>
+          {record.dbType && <code style={{ marginRight: 8 }}>{record.dbType}</code>}
+          {record.executedAt && formatRelativeTime(record.executedAt)}
+        </div>
+      </div>
+      <pre
+        style={{
+          margin: 0,
+          whiteSpace: 'pre-wrap',
+          wordBreak: 'break-all',
+          fontFamily: 'ui-monospace, Consolas, monospace',
+          fontSize: 11,
+          maxHeight: 80,
+          overflow: 'hidden',
+        }}
+      >
+        {record.sqlPreview || '(无 SQL 预览)'}
+      </pre>
+    </div>
+  )
+}
+
+// formatRelativeTime 把 ISO 时间字符串格式化为相对时间（"3分钟前"）。
+function formatRelativeTime(isoTime: string): string {
+  const ts = Date.parse(isoTime)
+  if (isNaN(ts)) return ''
+  const diffMs = Date.now() - ts
+  if (diffMs < 60_000) return '刚刚'
+  if (diffMs < 3600_000) return `${Math.floor(diffMs / 60_000)} 分钟前`
+  if (diffMs < 86400_000) return `${Math.floor(diffMs / 3600_000)} 小时前`
+  return `${Math.floor(diffMs / 86400_000)} 天前`
+}