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-gateway/src/lib.rs

@@ -0,0 +1,36 @@
+#![allow(
+    dead_code,
+    unused_assignments,
+    unused_imports,
+    unused_mut,
+    unused_variables,
+    clippy::bool_assert_comparison,
+    clippy::collapsible_if,
+    clippy::empty_line_after_outer_attr,
+    clippy::field_reassign_with_default,
+    clippy::if_same_then_else,
+    clippy::large_enum_variant,
+    clippy::manual_div_ceil,
+    clippy::manual_find,
+    clippy::match_like_matches_macro,
+    clippy::needless_as_bytes,
+    clippy::needless_lifetimes,
+    clippy::nonminimal_bool,
+    clippy::question_mark,
+    clippy::redundant_closure,
+    clippy::result_large_err,
+    clippy::too_many_arguments,
+    clippy::type_complexity,
+    clippy::useless_concat
+)]
+
+mod gateway;
+
+pub use gateway::exports::{
+    build_execution_runtime_router, build_execution_runtime_router_with_request_concurrency_limit,
+    build_execution_runtime_router_with_request_gates, build_router, build_router_with_state,
+    build_tunnel_runtime_router_with_state, serve_execution_runtime_tcp,
+    serve_execution_runtime_unix, serve_tcp, tunnel_protocol, AppState, FrontdoorCorsConfig,
+    FrontdoorUserRpmConfig, GatewayDataConfig, TunnelConnConfig, TunnelControlPlaneClient,
+    TunnelRuntimeState, UsageRuntimeConfig, VideoTaskTruthSourceMode,
+};