fix: 管理后台页面修复

- AdminLayout: 侧边栏布局和导航修复
- dal.ts: 数据访问层 API 调用修复
- Dashboard: 仪表盘统计卡片和数据加载修复
- Backtest: 回测配置和结果展示修复
- LLMConfig: LLM 配置页面修复
- Predictions: 预测管理页面修复

frontend/src/admin/pages/Backtest.tsx

@@ -61,7 +61,7 @@ function exportCsv(rows: BacktestResultRow[]) {
   const url = URL.createObjectURL(blob)
   const a = document.createElement("a")
   a.href = url
-  a.download = `backtest_${new Date().toISOString().slice(0, 10)}.csv`
+  a.download = `backtest_${new Date().toLocaleDateString('sv-SE')}.csv`
   a.click()
   URL.revokeObjectURL(url)
 }
@@ -73,7 +73,7 @@ function csvCell(v: string): string {
 
 function fmtDate(s?: string | null): string {
   if (!s) return '—'
-  return s.slice(0, 10)
+  return new Date(s).toLocaleDateString('sv-SE')
 }
 
 export default function BacktestPage() {
@@ -82,7 +82,7 @@ export default function BacktestPage() {
   const [dateFrom, setDateFrom] = useState('')
   const [dateTo, setDateTo] = useState('')
   const [limit, setLimit] = useState(20)
-  const [mode, setMode] = useState<'single' | 'multi'>('single')
+  const [mode] = useState<'multi'>('multi')
   const [model, setModel] = useState('')
   const [loading, setLoading] = useState(false)
   const [error, setError] = useState<string | null>(null)
@@ -193,14 +193,12 @@ export default function BacktestPage() {
                 </div>
                 <div>
                   <label className="mb-1.5 block text-xs text-ink-500">模式</label>
-                  <select
-                    value={mode}
-                    onChange={e => setMode(e.target.value as 'single' | 'multi')}
-                    className="field w-full"
-                  >
-                    <option value="single">单次调用 (快)</option>
-                    <option value="multi">多专家 (慢,贵)</option>
-                  </select>
+                  <input
+                    type="text"
+                    value="多专家 (5 路 + 终裁)"
+                    readOnly
+                    className="field w-full bg-paper-100 text-ink-500"
+                  />
                 </div>
               </div>
 
@@ -281,7 +279,7 @@ export default function BacktestPage() {
                   </div>
                   {summary.degraded > 0 && (
                     <div className="col-span-full border-l-2 border-press bg-press-wash/40 px-3 py-2 text-2xs leading-relaxed text-press-dark">
-                      有 {summary.degraded} 场预测降级(专家无有效结论),未计入准确率分子。建议检查该时段数据完整性或改用单次模式。
+                      有 {summary.degraded} 场预测降级(专家无有效结论),未计入准确率分子。建议检查该时段数据完整性。
                     </div>
                   )}
                 </div>