feat(stream-bridge): 支持上游 sync 响应转 SSE 流式输出，记录 client/upstream 流模式差异

- 新增 sync_to_stream 桥接模块，将非 SSE 上游响应转换为 SSE 格式回传给流式客户端
- stream_pump 检测非 SSE 响应头后缓冲整包并通过桥接逻辑重写为 SSE 帧
- proxy handler 同步支持 sync→stream 聚合与转换（覆盖 openai/claude/gemini 四种格式）
- sync_products 补全 openai:cli 的完整流式事件聚合（text delta、reasoning、tool call 等）
- usage runtime 写入 client_requested_stream / upstream_is_stream 到 request_metadata
- SQL 查询层将两个布尔字段从 request_metadata jsonb 中提取并回传给前端
- 前端 status.ts 新增 resolveUsageStreamLabelSegments，优先读取 client_requested_stream
- RequestDetailDrawer 在流式转换场景下显示"客户端→上游"两段 Badge

frontend/src/features/usage/components/UsageRecordsTable.vue

@@ -232,6 +232,17 @@
             >
               取消
             </Badge>
+            <Badge
+              v-else-if="getStreamModeSegments(record).hasConversion"
+              :variant="getStreamModeSegments(record).client === '流式' ? 'secondary' : 'outline'"
+              :class="getStreamModeSegments(record).client === '流式'
+                ? 'whitespace-nowrap text-[10px] px-1.5 h-4 leading-4 inline-flex items-center gap-0.5'
+                : 'whitespace-nowrap border-border/60 text-muted-foreground text-[10px] px-1.5 h-4 leading-4 inline-flex items-center gap-0.5'"
+            >
+              <span>{{ getStreamModeSegments(record).client }}</span>
+              <span class="opacity-60">→</span>
+              <span>{{ getStreamModeSegments(record).upstream }}</span>
+            </Badge>
             <Badge
               v-else
               :variant="getUpstreamStream(record) ? 'secondary' : 'outline'"
@@ -529,6 +540,17 @@
             >
               已取消
             </Badge>
+            <Badge
+              v-else-if="getStreamModeSegments(record).hasConversion"
+              :variant="getStreamModeSegments(record).client === '流式' ? 'secondary' : 'outline'"
+              :class="getStreamModeSegments(record).client === '流式'
+                ? 'whitespace-nowrap inline-flex items-center gap-1'
+                : 'whitespace-nowrap border-border/60 text-muted-foreground inline-flex items-center gap-1'"
+            >
+              <span>{{ getStreamModeSegments(record).client }}</span>
+              <span class="opacity-60">→</span>
+              <span>{{ getStreamModeSegments(record).upstream }}</span>
+            </Badge>
             <Badge
               v-else
               :variant="getUpstreamStream(record) ? 'secondary' : 'outline'"
@@ -672,7 +694,8 @@ import {
   formatUsageStreamLabel,
   isUsageRecordFailed,
   isUsageUpstreamStream,
-  resolveDisplayRequestStatus
+  resolveDisplayRequestStatus,
+  resolveUsageStreamLabelSegments
 } from '../utils/status'
 import { useRowClick } from '@/composables/useRowClick'
 import { formatApiFormat } from '@/api/endpoints/types/api-format'
@@ -763,6 +786,10 @@ function getStreamModeLabel(record: UsageRecord): string {
   return formatUsageStreamLabel(record)
 }
 
+function getStreamModeSegments(record: UsageRecord) {
+  return resolveUsageStreamLabelSegments(record)
+}
+
 function getUpstreamStream(record: UsageRecord): boolean {
   return isUsageUpstreamStream(record)
 }