feat(security): harden gateway boundaries and usage policies

Consolidate subscription usage policy enforcement, privacy-safe persistence, and gateway security hardening into one reviewable change.

Includes bounded HTTP and execution envelopes, header and protocol guards, DNS and relay validation, authentication and secret projection hardening, secure backup/install paths, and regression coverage.

apps/aether-gateway/src/handlers/admin/auth/api_keys/mod.rs

@@ -6,8 +6,7 @@ use super::super::users::{
 };
 use crate::handlers::admin::request::{AdminAppState, AdminRequestContext};
 use crate::handlers::admin::shared::{
-    decrypt_catalog_secret_with_fallbacks, encrypt_catalog_secret_with_fallbacks, query_param_bool,
-    query_param_optional_bool, query_param_value,
+    query_param_bool, query_param_optional_bool, query_param_value,
 };
 use crate::GatewayError;
 use axum::{
@@ -42,12 +41,14 @@ pub(crate) async fn maybe_build_local_admin_api_keys_response(
     state: &AdminAppState<'_>,
     request_context: &AdminRequestContext<'_>,
     request_headers: &http::HeaderMap,
+    remote_addr: &std::net::SocketAddr,
     request_body: Option<&axum::body::Bytes>,
 ) -> Result<Option<Response<Body>>, GatewayError> {
     routes::maybe_build_local_admin_api_keys_routes_response(
         state,
         request_context,
         request_headers,
+        remote_addr,
         request_body,
     )
     .await