feat(rust): 支持 image 同步转流式 SSE、free_team_first 调度预设及账户错误自动重试

- openai:image 同步响应桥接为流式 SSE（image_generation.completed / image_edit.completed 事件）
- image 请求解析与前置校验移除模型白名单，支持任意自定义模型名
- 调度器新增 free_team_first 预设（mode: both / free_only / team_only）
- pool config 解析重构：新增 POOL_ALLOWED_SCHEDULING_PRESETS 白名单，规范化 mode 字段
- 错误分类器新增账户/账单错误模式集，升级为 RetryUpstreamFailure 而非 StopSemanticClientError
- 修复 stream execution 中上游 headers 与输出 headers 混用导致 content-type 判断错误的问题
- codex image 工具始终写入 action 字段（generate/edit），仅 generate 操作填充默认 size/quality
- 前端：pool 节点组只展示实际执行过的候选节点，全部 skipped 时折叠为最后一个节点
- Redis 测试就绪检测从 TCP 连接改为 PING/PONG 协议验证

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

@@ -3,7 +3,9 @@ import { describe, expect, it } from 'vitest'
 import type { CandidateRecord } from '@/api/requestTrace'
 import {
   buildPoolAttemptCandidatesFromAudit,
+  buildPoolGroupVisibleAttempts,
   buildPoolParticipatedCandidates,
+  isAttemptedCandidate,
 } from '@/features/usage/utils/poolTrace'
 
 function buildCandidate(
@@ -170,4 +172,61 @@ describe('poolTrace', () => {
     expect(attempts.map(item => item.key_id)).toEqual(['key-success', 'key-skipped'])
     expect(attempts[1].extra_data?.pool_group_id).toBe('provider-1')
   })
+
+  it('treats only real execution statuses as attempted', () => {
+    expect(isAttemptedCandidate(buildCandidate({ status: 'success' }))).toBe(true)
+    expect(isAttemptedCandidate(buildCandidate({ status: 'failed' }))).toBe(true)
+    expect(isAttemptedCandidate(buildCandidate({ status: 'cancelled' }))).toBe(true)
+    expect(isAttemptedCandidate(buildCandidate({ status: 'streaming' }))).toBe(true)
+    expect(isAttemptedCandidate(buildCandidate({ status: 'stream_interrupted' }))).toBe(true)
+    expect(isAttemptedCandidate(buildCandidate({ status: 'pending' }))).toBe(false)
+    expect(isAttemptedCandidate(buildCandidate({
+      status: 'pending',
+      started_at: '2026-04-24T12:00:00.000Z',
+    }))).toBe(true)
+    expect(isAttemptedCandidate(buildCandidate({ status: 'skipped' }))).toBe(false)
+    expect(isAttemptedCandidate(buildCandidate({ status: 'available' }))).toBe(false)
+    expect(isAttemptedCandidate(buildCandidate({ status: 'unused' }))).toBe(false)
+  })
+
+  it('shows only attempted pool children when attempted nodes exist', () => {
+    const attempts = buildPoolGroupVisibleAttempts([
+      buildCandidate({
+        id: 'cand-skipped',
+        candidate_index: 0,
+        status: 'skipped',
+      }),
+      buildCandidate({
+        id: 'cand-failed',
+        candidate_index: 1,
+        status: 'failed',
+        started_at: '2026-04-24T12:00:00.000Z',
+      }),
+      buildCandidate({
+        id: 'cand-success',
+        candidate_index: 2,
+        status: 'success',
+        started_at: '2026-04-24T12:00:01.000Z',
+      }),
+    ])
+
+    expect(attempts.map(item => item.id)).toEqual(['cand-failed', 'cand-success'])
+  })
+
+  it('collapses all-skipped pool nodes to a single provider node', () => {
+    const attempts = buildPoolGroupVisibleAttempts([
+      buildCandidate({
+        id: 'cand-skipped-1',
+        candidate_index: 0,
+        status: 'skipped',
+      }),
+      buildCandidate({
+        id: 'cand-skipped-2',
+        candidate_index: 1,
+        status: 'skipped',
+      }),
+    ])
+
+    expect(attempts.map(item => item.id)).toEqual(['cand-skipped-2'])
+  })
 })

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

@@ -45,6 +45,39 @@ export const isPoolParticipatedCandidate = (candidate: CandidateRecord): boolean
   return true
 }
 
+export const isAttemptedCandidate = (
+  candidate: Pick<CandidateRecord, 'status' | 'started_at'>,
+): boolean => {
+  switch (candidate.status) {
+    case 'streaming':
+    case 'success':
+    case 'failed':
+    case 'cancelled':
+    case 'stream_interrupted':
+      return true
+    case 'pending':
+      return Boolean(candidate.started_at)
+    case 'available':
+    case 'unused':
+    case 'skipped':
+    default:
+      return false
+  }
+}
+
+export function buildPoolGroupVisibleAttempts(
+  attempts: CandidateRecord[],
+): CandidateRecord[] {
+  if (attempts.length === 0) return []
+
+  const attempted = attempts.filter(isAttemptedCandidate)
+  if (attempted.length > 0) {
+    return attempted
+  }
+
+  return [attempts[attempts.length - 1]]
+}
+
 export const parseTimelineStatus = (value: unknown): CandidateRecord['status'] | null => {
   if (typeof value !== 'string') return null
   const normalized = value.trim().toLowerCase()