refactor: 移除独立 hub/proxy/executor/gateway crate，统一为 gateway tunnel 架构

- 删除 aether-hub、aether-proxy 独立项目及其 Dockerfile/配置
- 删除 crates/aether-executor 和 crates/aether-gateway 全部模块
- 新增 apps/ 目录作为应用入口
- 将 hub 概念重构为 gateway tunnel transport
- 将 executor 重构为 execution runtime
- 新增 tunnel.rs 合约定义和 testkit tunnel/execution_runtime 模块
- 更新 Python 服务层和测试适配新架构命名

apps/aether-proxy/Cargo.toml

@@ -0,0 +1,45 @@
+[package]
+name = "aether-proxy"
+version = "0.2.5"
+edition = "2021"
+description = "Tunnel proxy for Aether"
+
+[dependencies]
+aether-contracts.workspace = true
+aether-http.workspace = true
+aether-runtime.workspace = true
+tokio = { version = "1", features = ["full"] }
+reqwest.workspace = true
+hyper = { version = "1", features = ["client", "http1", "http2"] }
+hyper-util = { version = "0.1", features = ["client", "client-legacy", "http1", "http2", "tokio"] }
+http-body-util = "0.1"
+tokio-tungstenite = { version = "0.24", features = ["rustls-tls-webpki-roots"] }
+tokio-rustls = "0.26"
+futures-util = "0.3"
+base64 = "0.22"
+clap = { version = "4", features = ["derive", "env"] }
+tracing = "0.1"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+thiserror = "2"
+bytes = "1"
+sha2 = "0.10"
+hex = "0.4"
+anyhow = "1"
+arc-swap = "1"
+toml = "0.8"
+rustls = { version = "0.23", features = ["ring"] }
+ratatui = "0.30"
+crossterm = "0.28"
+url = "2"
+sysinfo = "0.32"
+libc = "0.2"
+flate2 = "1"
+tar = "0.4"
+socket2 = { version = "0.5", features = ["all"] }
+tower-service = "0.3"
+webpki-roots = "0.26"
+
+[dev-dependencies]
+aether-gateway.workspace = true
+axum.workspace = true