feat(proxy,failover,transport): Hyper 上游客户端精细计时、连续失败退避与连接泄漏修复

Proxy:
- 将上游 HTTP 客户端从 reqwest 替换为 hyper，新增 InstrumentedConnector
  实现 TCP 连接/TLS 握手级别的独立计时，上报 connection_reused 等指标
- 前端展示细粒度代理计时（连接复用、等待响应头等）

Failover:
- 引入连续失败退避机制，每 10 次失败递增退避间隔
- 检测 H2 max outbound streams 错误并触发上游客户端重建
- 新增 HTTPClientPool.reset_upstream_client 支持按需重建缓存客户端

连接泄漏修复:
- Handler 异常路径确保 response_ctx 被正确关闭
- HubResponseStream 迭代结束后在 finally 块中清理 stream_id
- HubTunnelTransport.handle_request 捕获所有异常并清理流状态

aether-proxy/Cargo.lock

@@ -10,7 +10,7 @@ checksum = "320119579fcad9c21884f5c4861d16174d0e06250625266f50fe6898340abefa"
 
 [[package]]
 name = "aether-proxy"
-version = "0.2.2"
+version = "0.2.3"
 dependencies = [
  "anyhow",
  "arc-swap",
@@ -21,6 +21,9 @@ dependencies = [
  "flate2",
  "futures-util",
  "hex",
+ "http-body-util",
+ "hyper",
+ "hyper-util",
  "libc",
  "ratatui",
  "reqwest",
@@ -33,8 +36,10 @@ dependencies = [
  "tar",
  "thiserror 2.0.18",
  "tokio",
+ "tokio-rustls",
  "tokio-tungstenite",
  "toml",
+ "tower-service",
  "tracing",
  "tracing-subscriber",
  "url",