feat: delegate 客户端替换为 hyper 原生实现，新增代理管理功能

aether-proxy:
- 用 hyper-util Client + 自定义 InstrumentedConnector 替换 reqwest delegate 客户端
- 支持 HTTP/HTTPS 自动 TLS，ALPN h2 协商，connect/tls 分阶段计时
- ConnectTiming 通过 hyper extensions 传递，上游响应细分 connect_ms/tls_ms/ttfb_ms
- upgrade 命令在非 root 下跳过 systemd restart 并提示手动操作

后端:
- 新增 /admin/proxy-nodes/test-url 接口，支持直接测试代理 URL 连通性
- 新增 /admin/proxy-nodes/hmac-key 接口，获取 HMAC Key 供部署使用
- 提取 _test_proxy_connectivity 公共函数，消除 test_node 中的重复代码
- candidate_resolver 在 extra_data 中输出 needs_conversion/provider_api_format
- stats_aggregator 小时聚合增加 IntegrityError 冲突重试

前端:
- 请求时间线组件展示代理 timing 细分（DNS/连接/TLS/TTFB/上游处理）
- 请求时间线增加格式转换分界标记和 conversion badge
- ProxyNodes 页面新增代理 URL 测试和 HMAC Key 复制功能
- HardwareTooltip 从 Popover 改为 Tooltip 组件

aether-proxy/Cargo.toml

@@ -7,7 +7,8 @@ description = "Forward proxy for Aether with HMAC authentication"
 [dependencies]
 tokio = { version = "1", features = ["full"] }
 hyper = { version = "1", features = ["http1", "server"] }
-hyper-util = { version = "0.1", features = ["tokio", "http1", "server"] }
+hyper-util = { version = "0.1", features = ["tokio", "http1", "http2", "server", "client-legacy"] }
+tower-service = "0.3"
 http-body-util = "0.1"
 reqwest = { version = "0.12", default-features = false, features = ["json", "rustls-tls", "stream", "http2"] }
 futures-util = "0.3"
@@ -26,6 +27,7 @@ hex = "0.4"
 anyhow = "1"
 toml = "0.8"
 tokio-rustls = "0.26"
+webpki-roots = "1"
 rustls = { version = "0.23", features = ["ring"] }
 rustls-pki-types = "1"
 rustls-pemfile = "2"