feat: 新增 frontdoor 执行回环守卫与多项可观测性增强

- 新增 frontdoor_loop_guard 模块，检测并拒绝 execution runtime 回环到本地网关的请求（HTTP 508）
- candidate loop 引入 span tracking、执行尝试日志与流式看门狗超时
- 本地故障转移策略支持从 report_context 加载，新增 append_local_failover_policy_to_value
- runtime tracing 美化：移除 identity 前缀，按 span 深度树形缩进，target 固定宽度展示
- Codex OpenAI CLI 补齐 chatgpt-account-id/x-client-request-id/session_id/conversation_id 请求头
- OpenAI CLI same/cross-format 聚合规则放宽以支持 openai:compact 客户端格式，并过滤 error-like 响应体
- auth/proxy/finalize 日志补充 user_id/api_key_id/api_key_name/balance_remaining 等字段
- 启动日志拆分为 starting/ready/config 三段，新增 resolve_bind_http_base_url
- access_log middleware 将生成的 trace_id 回注到下游请求头
- Cargo.toml 启用 serde_json preserve_order 特性

crates/aether-admin/src/observability/usage.rs

@@ -288,7 +288,11 @@ mod tests {
 
     #[test]
     fn explicit_completed_status_wins_over_legacy_failure_fields() {
-        let item = sample_usage("completed", Some(429), Some("rate limited on first attempt"));
+        let item = sample_usage(
+            "completed",
+            Some(429),
+            Some("rate limited on first attempt"),
+        );
         assert!(!admin_usage_is_failed(&item));
         assert!(!admin_usage_matches_status(&item, Some("failed")));
         assert!(admin_usage_matches_status(&item, Some("completed")));