feat(comparison-records): 比价记录展示 LLM 实际成本(列表列 + 详情 + 价格快照)

- 列表「成本」列优先显示后端冻结的实际成本(当时价/绿色),无则回退前端估算(灰色)
- 详情抽屉「LLM 成本」:有 llm_cost_yuan 显示实际值 +「实际·当时价」标,无则回退估算;
  另展示所用单价快照 JSON
- types.ts:ComparisonRecordListItem 加 llm_cost_yuan(详情继承)
- 顺带:InputNumber addonAfter → suffix(消 antd 弃用警告);详情 llm_calls 遍历对
  input_messages 加空值防御(残缺数据不再整页白屏)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/(main)/comparison-records/page.tsx

@@ -215,7 +215,16 @@ export default function ComparisonRecordsPage() {
       title: '成本',
       key: 'cost',
       width: 90,
-      render: (_, r) => fmtCost(calcCost(r.input_tokens, r.output_tokens, pricePerMTok)),
+      // 有后端冻结的实际成本(当时价)就用它;否则回退老的前端估算(需顶部填 LLM 单价)。
+      render: (_, r) => {
+        if (r.llm_cost_yuan != null) {
+          return <span title="实际成本（按调用时单价冻结）" style={{ color: '#389e0d' }}>{fmtCost(r.llm_cost_yuan)}</span>;
+        }
+        const est = calcCost(r.input_tokens, r.output_tokens, pricePerMTok);
+        return est == null
+          ? '-'
+          : <span title="估算（顶部 LLM 单价 × token）" style={{ color: '#999' }}>{fmtCost(est)}</span>;
+      },
     },
     {
       title: '机型/ROM',
@@ -292,7 +301,7 @@ export default function ComparisonRecordsPage() {
           min={0}
           step={0.1}
           style={{ width: 210 }}
-          addonAfter="元/百万token"
+          suffix="元/百万token"
         />
       </Space>
 
@@ -331,12 +340,27 @@ export default function ComparisonRecordsPage() {
                   ? '-'
                   : `${detail.input_tokens ?? 0} / ${detail.output_tokens ?? 0} / ${(detail.input_tokens ?? 0) + (detail.output_tokens ?? 0)}`}
               </Descriptions.Item>
-              <Descriptions.Item label="估算成本">
-                {fmtCost(calcCost(detail.input_tokens, detail.output_tokens, pricePerMTok))}
-                {pricePerMTok == null && (detail.input_tokens != null || detail.output_tokens != null)
-                  ? <span style={{ color: '#999', fontSize: 12 }}>（顶部填 LLM 单价后显示）</span>
-                  : null}
+              <Descriptions.Item label="LLM 成本">
+                {detail.llm_cost_yuan != null ? (
+                  <>
+                    {fmtCost(detail.llm_cost_yuan)}
+                    <Tag color="green" style={{ marginLeft: 6 }}>实际·当时价</Tag>
+                  </>
+                ) : (
+                  <>
+                    {fmtCost(calcCost(detail.input_tokens, detail.output_tokens, pricePerMTok))}
+                    <span style={{ color: '#999', fontSize: 12, marginLeft: 6 }}>估算</span>
+                    {pricePerMTok == null && (detail.input_tokens != null || detail.output_tokens != null)
+                      ? <span style={{ color: '#999', fontSize: 12 }}>（顶部填 LLM 单价后显示）</span>
+                      : null}
+                  </>
+                )}
               </Descriptions.Item>
+              {detail.llm_price_snapshot ? (
+                <Descriptions.Item label="价格快照" span={2}>
+                  <pre style={preStyle}>{JSON.stringify(detail.llm_price_snapshot, null, 2)}</pre>
+                </Descriptions.Item>
+              ) : null}
               <Descriptions.Item label="源平台">{detail.source_platform_name || '-'}（{cents(detail.source_price_cents)}）</Descriptions.Item>
               <Descriptions.Item label="最优">{detail.best_platform_name || '-'}（{cents(detail.best_price_cents)}）</Descriptions.Item>
               <Descriptions.Item label="省" span={2}>{cents(detail.saved_amount_cents)}{detail.is_source_best ? '（源平台最便宜）' : ''}</Descriptions.Item>
@@ -432,7 +456,7 @@ export default function ComparisonRecordsPage() {
                     ),
                     children: (
                       <div>
-                        {c.input_messages.map((m, j) => (
+                        {(c.input_messages ?? []).map((m, j) => (
                           <div key={j} style={{ marginBottom: 8 }}>
                             <Tag>{m.role}</Tag>
                             <pre style={preStyle}>{pretty(m.content)}</pre>

src/lib/types.ts

@@ -354,6 +354,7 @@ export interface ComparisonRecordListItem {
   retry_count: number | null;
   input_tokens: number | null;
   output_tokens: number | null;
+  llm_cost_yuan: number | null;   // 后端按「当时价」冻结的实际成本(元);旧记录 null → 「成本」列回退估算
   device_model: string | null;
   rom_vendor: string | null;
   rom_name: string | null;
@@ -396,6 +397,8 @@ export interface ComparisonRecordDetail extends ComparisonRecordListItem {
   latitude: number | null;
   llm_calls: LlmCall[] | null;
   raw_payload: Record<string, unknown> | null;
+  // 算成本所用单价快照 {mode, prices:{model:{...}}}(llm_cost_yuan 继承自列表项)。
+  llm_price_snapshot: Record<string, unknown> | null;
 }
 
 export interface AdRevenueImpression {