fix(gateway): route Codex header through serving facade

apps/aether-gateway/src/ai_serving/api.rs

@@ -68,6 +68,7 @@ pub(crate) use aether_ai_formats::api::{
     OPENAI_VIDEO_REMIX_SYNC_PLAN_KIND,
 };
 pub(crate) use aether_ai_formats::protocol::stream::CanonicalUsage as StreamingCanonicalUsage;
+pub(crate) use aether_ai_formats::CODEX_RESPONSES_LITE_HEADER;
 
 pub(crate) fn parse_direct_request_body(
     parts: &http::request::Parts,

apps/aether-gateway/src/ai_serving/mod.rs

@@ -13,7 +13,9 @@ use crate::{usage::GatewaySyncReportRequest, AppState, GatewayError};
 pub(crate) use self::adaptation::{
     maybe_build_provider_private_stream_normalizer, ProviderPrivateStreamNormalizer,
 };
-pub(crate) use self::api::gemini_generate_content_response_has_visible_output;
+pub(crate) use self::api::{
+    gemini_generate_content_response_has_visible_output, CODEX_RESPONSES_LITE_HEADER,
+};
 pub(crate) use self::finalize::common::LocalCoreSyncFinalizeOutcome;
 pub(crate) use self::finalize::internal::{
     maybe_bridge_standard_sync_json_to_stream, maybe_build_stream_response_rewriter,

apps/aether-gateway/src/ai_serving/planner/decision_input.rs

@@ -1,7 +1,6 @@
 use std::collections::BTreeMap;
 use std::time::Duration;
 
-use aether_ai_formats::CODEX_RESPONSES_LITE_HEADER;
 use aether_ai_serving::{run_ai_authenticated_decision_input, AiAuthenticatedDecisionInputPort};
 use aether_routing_core::{
     rank_vector_for_candidate, CandidateKind, ResolvedRoutingPolicy, RoutingCandidateFacts,
@@ -17,7 +16,7 @@ use tracing::warn;
 use crate::ai_serving::planner::common::extract_standard_requested_model;
 use crate::ai_serving::{
     ExecutionRuntimeAuthContext, GatewayAuthApiKeySnapshot, GatewayProviderTransportSnapshot,
-    PlannerAppState,
+    PlannerAppState, CODEX_RESPONSES_LITE_HEADER,
 };
 use crate::client_session_affinity::client_session_affinity_from_request;
 use crate::clock::current_unix_secs;