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

apps/aether-gateway/src/tests/frontdoor/ai.rs

@@ -7,7 +7,7 @@ use super::{
 use crate::tests::{
     any, build_router_with_state, build_state_with_execution_runtime_override, json, start_server,
     to_bytes, AppState, Arc, Body, Json, Mutex, Request, Router, StatusCode, EXECUTION_PATH_HEADER,
-    EXECUTION_PATH_LOCAL_AI_PUBLIC,
+    EXECUTION_PATH_LOCAL_AI_PUBLIC, EXECUTION_PATH_LOCAL_EXECUTION_RUNTIME_MISS,
 };
 use axum::response::IntoResponse;
 
@@ -522,7 +522,7 @@ async fn gateway_rejects_invalid_claude_count_tokens_payload_without_hitting_fal
 }
 
 #[tokio::test]
-async fn gateway_rejects_gpt_image_2_on_chat_completions_without_hitting_fallback_probe() {
+async fn gateway_does_not_locally_reject_image_model_name_on_chat_completions() {
     let fallback_probe_hits = Arc::new(Mutex::new(0usize));
     let fallback_probe_hits_clone = Arc::clone(&fallback_probe_hits);
     let fallback_probe = Router::new().route(
@@ -567,18 +567,13 @@ async fn gateway_rejects_gpt_image_2_on_chat_completions_without_hitting_fallbac
         .await
         .expect("request should succeed");
 
-    assert_eq!(response.status(), StatusCode::BAD_REQUEST);
+    assert_eq!(response.status(), StatusCode::SERVICE_UNAVAILABLE);
     assert_eq!(
         response
             .headers()
             .get(EXECUTION_PATH_HEADER)
             .and_then(|value| value.to_str().ok()),
-        Some(EXECUTION_PATH_LOCAL_AI_PUBLIC)
-    );
-    let payload: serde_json::Value = response.json().await.expect("json body should parse");
-    assert_eq!(
-        payload["detail"],
-        "图片模型仅支持通过 /v1/images/generations、/v1/images/edits 或 /v1/images/variations 调用"
+        Some(EXECUTION_PATH_LOCAL_EXECUTION_RUNTIME_MISS)
     );
     assert_eq!(*fallback_probe_hits.lock().expect("mutex should lock"), 0);