feat: 提前记录 pending 用量、优化流遥测时序与前端活跃请求发现机制

- 将 record_pending 调用移至执行开始前（sync/stream 两路），确保请求在执行前即有 pending 记录
- stream_pump 在收到第一个数据块前优先 yield 遥测帧，保证 ttfb 早于 data 帧到达
- stream execution 增加 should_refresh_stream_usage_telemetry，在遥测帧携带新 ttfb/elapsed 时及时更新 record_stream_started
- access_log 对高频轮询路径（usage/active、usage/records 等）降级为 TRACE 日志，减少日志噪音
- 前端新增 reconcileActiveRequestDiscovery 工具函数及 discoverActiveRequests 逻辑，活跃请求发现与全局自动刷新解耦，空闲时降频为 5 秒扫描
- RequestDetailDrawer 调整：进行中请求不再自动开启轮询，由用户手动触发；刷新按钮 title 动态适配状态

apps/aether-gateway/src/handlers/proxy/finalize.rs

@@ -7,13 +7,13 @@ use crate::constants::{
 };
 use crate::control::GatewayControlDecision;
 use crate::control::GatewayPublicRequestContext;
-use crate::middleware::RequestLogEmitted;
+use crate::middleware::{should_downgrade_access_log, RequestLogEmitted};
 use crate::AppState;
 use aether_runtime::{maybe_hold_axum_response_permit, AdmissionPermit};
 use axum::body::{Body, Bytes};
 use axum::http::{self, header::HeaderName, header::HeaderValue, Response};
 use std::time::Instant;
-use tracing::{info, warn};
+use tracing::{info, trace, warn};
 
 pub(super) fn request_wants_stream(
     request_context: &GatewayPublicRequestContext,
@@ -113,6 +113,24 @@ pub(super) fn finalize_gateway_response(
             elapsed_ms,
             "gateway request failed"
         );
+    } else if should_downgrade_access_log(method, path_and_query) {
+        trace!(
+            event_name = "http_request_completed",
+            log_type = "access",
+            status = "completed",
+            status_code,
+            trace_id = %trace_id,
+            request_id,
+            remote_addr = %remote_addr,
+            method = %method,
+            path = %path_and_query,
+            route_class,
+            execution_path,
+            dependency_reason = dependency_reason.as_str(),
+            local_execution_runtime_miss_reason = local_execution_runtime_miss_reason.as_str(),
+            elapsed_ms,
+            "gateway completed request"
+        );
     } else {
         info!(
             event_name = "http_request_completed",