[sgl-router] refactor - move policy-required states under src/state (#40272)

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

experimental/sgl-router/tests/proxy/header_forwarding.rs

@@ -4,7 +4,7 @@
 use axum::body::Body;
 use axum::http::Request;
 use sgl_router::config::{
-    ActiveLoadConfig, Config, DiscoveryBackend, ModelConfig, ObservabilityConfig, PolicyKind,
+    Config, DiscoveryBackend, InflightLoadConfig, ModelConfig, ObservabilityConfig, PolicyKind,
     ProxyConfig, ServerConfig, StaticUrlsDiscoveryConfig,
 };
 use sgl_router::discovery::{ModelId, WorkerId, WorkerMode, WorkerSpec};
@@ -47,7 +47,7 @@ async fn forwards_whitelisted_headers_strips_others() {
             urls: vec!["http://placeholder:0".into()],
         }),
         proxy: ProxyConfig::default(),
-        active_load: ActiveLoadConfig::default(),
+        router_inflight_load: InflightLoadConfig::default(),
     };
     let tokenizers = Arc::new(TokenizerRegistry::load_from_config(&cfg).unwrap());
     let registry = Arc::new(WorkerRegistry::default());