feat(intelligent-eval): adjust drawer top-bar layout

详情页移除返回列表按钮（抽屉自带关闭），操作按钮右对齐；
报告页保留返回详情，导出 Markdown 按钮右对齐。

frontend/web/src/components/intelligent_eval/EvalDetail.tsx

@@ -2,7 +2,7 @@ import { useCallback, useEffect, useState } from 'react'
 import {
   Alert, Button, Card, Descriptions, Empty, Input, Modal, Popconfirm, Space, Spin, Tag, message,
 } from 'antd'
-import { ArrowLeftOutlined, FileTextOutlined, StopOutlined } from '@ant-design/icons'
+import { FileTextOutlined, StopOutlined } from '@ant-design/icons'
 import { intelligentEvalsApi, type IntelligentEval, type IntelligentEvalSession } from '../../api'
 import { colors } from '../../tokens'
 import { formatDateTime, shortDateTime } from '../../utils/date'
@@ -63,12 +63,11 @@ function PlanView({ ev }: { ev: IntelligentEval }) {
 interface EvalDetailProps {
   ev: IntelligentEval
   targetName: string
-  onBack: () => void
   onOpenReport: () => void
   onChanged: () => void
 }
 
-export default function EvalDetail({ ev, targetName, onBack, onOpenReport, onChanged }: EvalDetailProps) {
+export default function EvalDetail({ ev, targetName, onOpenReport, onChanged }: EvalDetailProps) {
   const [busy, setBusy] = useState(false)
   const [rejectOpen, setRejectOpen] = useState(false)
   const [feedback, setFeedback] = useState('')
@@ -110,10 +109,11 @@ export default function EvalDetail({ ev, targetName, onBack, onOpenReport, onCha
 
   return (
     <div style={{ height: '100%', overflowY: 'auto', padding: '0 16px 16px' }}>
-      <Space style={{ marginBottom: 12 }}>
+      <div style={{ display: 'flex', alignItems: 'center', gap: 8, marginBottom: 12 }}>
-        <Button icon={<ArrowLeftOutlined />} onClick={onBack}>返回列表</Button>
         <span style={{ fontSize: 16, fontWeight: 600, color: colors.text }}>{ev.name}</span>
         <Tag color={meta.color}>{meta.label}</Tag>
+        <div style={{ flex: 1 }} />
+        <Space>
           {ev.status === 'completed' && (
             <Button type="primary" icon={<FileTextOutlined />} onClick={onOpenReport}>查看报告</Button>
           )}
@@ -123,6 +123,7 @@ export default function EvalDetail({ ev, targetName, onBack, onOpenReport, onCha
             </Popconfirm>
           )}
         </Space>
+      </div>
 
       <Card size="small" title="基本信息" style={sectionCard}>
         <Descriptions column={3} size="small">

frontend/web/src/components/intelligent_eval/EvalReport.tsx

@@ -146,17 +146,18 @@ export default function EvalReport({ ev, onBack }: EvalReportProps) {
 
   return (
     <div style={{ height: '100%', overflowY: 'auto', padding: '0 16px 16px' }}>
-      <Space style={{ marginBottom: 12 }}>
+      <div style={{ display: 'flex', alignItems: 'center', gap: 8, marginBottom: 12 }}>
         <Button icon={<ArrowLeftOutlined />} onClick={onBack}>返回详情</Button>
         <span style={{ fontSize: 16, fontWeight: 600, color: colors.text }}>
           {ev.name} · 评估报告
         </span>
+        <div style={{ flex: 1 }} />
         {report && (
           <Button icon={<DownloadOutlined />} loading={exporting} onClick={exportMarkdown}>
             导出 Markdown
           </Button>
         )}
-      </Space>
+      </div>
 
       {reportLoading && <Spin />}
 

frontend/web/src/pages/IntelligentEvals.tsx

@@ -197,7 +197,6 @@ export default function IntelligentEvalsPage() {
           <EvalDetail
             ev={selected}
             targetName={targetName(selected.target_id)}
-            onBack={closeDrawer}
             onOpenReport={() => setDrawerView('report')}
             onChanged={() => setDetailTick((t) => t + 1)}
           />