Fix/usage transfer filter (#307)

* fix(usage): 恢复 usage 列表中的 fallback 路由信号

* fix(admin): 支持 usage 记录展示和筛选 fallback 转移

* fix(usage): 在用户 usage 记录中暴露 fallback 标记

* fix(usage): 共享 usage 页面支持 fallback 筛选

* fix(usage): 对齐 fallback 筛选相关前端类型

* fix(usage): propagate has_fallback through active polling

---------

Co-authored-by: fawney19 <[email protected]>

frontend/src/features/usage/utils/__tests__/status.spec.ts

@@ -1,6 +1,7 @@
 import { describe, expect, it } from 'vitest'
 
 import {
+  hasUsageFallback,
   isUsageRecordFailed,
   isUsageRecordSuccessful,
   mapRequestStatusToTimelineStatus,
@@ -91,6 +92,12 @@ describe('usage status helpers', () => {
     })).toBe('failed')
   })
 
+  it('uses explicit has_fallback flag for transfer filtering', () => {
+    expect(hasUsageFallback(buildUsageRecord({ has_fallback: true }))).toBe(true)
+    expect(hasUsageFallback(buildUsageRecord({ has_fallback: false }))).toBe(false)
+    expect(hasUsageFallback(buildUsageRecord({ has_fallback: undefined }))).toBe(false)
+  })
+
   it('uses status code only as a last fallback for timeline status', () => {
     expect(resolveTimelineFinalStatus({
       statusCode: 200,

frontend/src/features/usage/utils/status.ts

@@ -11,6 +11,12 @@ function hasLegacyFailureSignal(
     (typeof record.error_message === 'string' && record.error_message.trim().length > 0)
 }
 
+export function hasUsageFallback(
+  record: Pick<UsageRecord, 'has_fallback'>
+): boolean {
+  return record.has_fallback === true
+}
+
 function hasTerminalSuccessStatusCode(
   record: Pick<UsageRecord, 'status_code'>
 ): boolean {