Add manual routing policy for router (#15586)

sgl-model-gateway/src/observability/metrics.rs

@@ -190,6 +190,10 @@ pub fn init_metrics() {
         "smg_worker_errors_total",
         "Worker-level errors by worker_type, connection_mode, error_type"
     );
+    describe_counter!(
+        "smg_worker_manual_policy_branch_total",
+        "Manual policy execution branch by branch type"
+    );
 
     // Layer 3: Worker resilience metrics (circuit breaker)
     describe_gauge!(
@@ -810,6 +814,15 @@ impl Metrics {
         .set(count as f64);
     }
 
+    /// Record manual policy execution branch
+    pub fn record_worker_manual_policy_branch(branch: &'static str) {
+        counter!(
+            "smg_worker_manual_policy_branch_total",
+            "branch" => branch
+        )
+        .increment(1);
+    }
+
     /// Set worker health status
     pub fn set_worker_health(worker_url: &str, healthy: bool) {
         gauge!(