feat: ProxyNode 代理节点管理系统与 OpenAI Responses API 解析增强

ProxyNode 系统：新增 aether-proxy（Rust）海外 VPS 代理组件，后端实现节点注册/心跳/
HMAC 认证/健康检测调度器/模块化集成，前端新增代理节点管理页面。ProxyConfig 支持
node_id 模式，http_client 支持 HMAC 签名代理 URL 构建与 TTL 缓存。

OpenAI CLI 解析器：适配 Responses API 格式，支持 input_tokens/output_tokens 提取、
output[].content[].text 文本解析、response.completed 流式事件 usage 嵌套结构。

aether-proxy/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "aether-proxy"
+version = "0.1.0"
+edition = "2021"
+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"] }
+http-body-util = "0.1"
+reqwest = { version = "0.12", features = ["json"] }
+hmac = "0.12"
+sha2 = "0.10"
+subtle = "2"
+base64 = "0.22"
+clap = { version = "4", features = ["derive", "env"] }
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter", "json"] }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+thiserror = "2"
+bytes = "1"
+hex = "0.4"
+anyhow = "1"
+
+[profile.release]
+lto = true
+strip = true
+codegen-units = 1