[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/component/policies/decode.rs

@@ -12,8 +12,10 @@ use sgl_router::policies::decode::{
     resolve_decode_with_capacity_fallback, DecodePolicy, DecodePowerOfTwoPolicy,
     DecodeSelectionContext, LegacyHostAffinityDecodePolicy,
 };
-use sgl_router::policies::engine_load::{EngineLoadSnapshot, NativeCacheWorkerLoad};
 use sgl_router::policies::SelectionProposal;
+use sgl_router::state::load_monitor::engine_reported_load::{
+    EngineReportedLoadSnapshot, EngineReportedSchedulingLoad,
+};
 use sgl_router::workers::Worker;
 use std::collections::HashMap;
 use std::sync::atomic::Ordering;
@@ -30,15 +32,15 @@ fn worker(id: &str) -> Arc<Worker> {
     }))
 }
 
-fn snapshot(entries: &[(&Arc<Worker>, u64, u64, u64, u64)]) -> EngineLoadSnapshot {
-    EngineLoadSnapshot::from_native_cache_workers(
+fn snapshot(entries: &[(&Arc<Worker>, u64, u64, u64, u64)]) -> EngineReportedLoadSnapshot {
+    EngineReportedLoadSnapshot::from_native_cache_workers(
         7,
         entries
             .iter()
             .map(|(worker, running, waiting, used, capacity)| {
                 (
                     worker.url.clone(),
-                    NativeCacheWorkerLoad {
+                    EngineReportedSchedulingLoad {
                         num_running_reqs: *running,
                         num_waiting_reqs: *waiting,
                         num_waiting_uncached_tokens: *waiting,