[router] consolidate worker get loads (#10880)

sgl-router/src/protocols/worker_spec.rs

@@ -215,3 +215,28 @@ pub struct FlushCacheResult {
     /// Human-readable summary message
     pub message: String,
 }
+
+/// Result from getting worker loads
+#[derive(Debug, Clone, Deserialize, Serialize)]
+pub struct WorkerLoadsResult {
+    /// Worker URL and load pairs
+    pub loads: Vec<WorkerLoadInfo>,
+    /// Total number of workers
+    pub total_workers: usize,
+    /// Number of workers with successful load fetches
+    pub successful: usize,
+    /// Number of workers with failed load fetches
+    pub failed: usize,
+}
+
+/// Individual worker load information
+#[derive(Debug, Clone, Deserialize, Serialize)]
+pub struct WorkerLoadInfo {
+    /// Worker URL
+    pub worker: String,
+    /// Worker type (regular, prefill, decode)
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub worker_type: Option<String>,
+    /// Current load (-1 indicates failure to fetch)
+    pub load: isize,
+}