feat(metrics): add frontend and backend protocol distribution metrics

ts/proxies/smart-proxy/models/metrics-types.ts

@@ -32,6 +32,23 @@ export interface IThroughputHistoryPoint {
 /**
  * Main metrics interface with clean, grouped API
  */
+/**
+ * Protocol distribution for frontend (client→proxy) or backend (proxy→upstream).
+ * Tracks active and total counts for h1/h2/h3/ws/other.
+ */
+export interface IProtocolDistribution {
+  h1Active: number;
+  h1Total: number;
+  h2Active: number;
+  h2Total: number;
+  h3Active: number;
+  h3Total: number;
+  wsActive: number;
+  wsTotal: number;
+  otherActive: number;
+  otherTotal: number;
+}
+
 export interface IMetrics {
   // Connection metrics
   connections: {
@@ -40,6 +57,8 @@ export interface IMetrics {
     byRoute(): Map<string, number>;
     byIP(): Map<string, number>;
     topIPs(limit?: number): Array<{ ip: string; count: number }>;
+    frontendProtocols(): IProtocolDistribution;
+    backendProtocols(): IProtocolDistribution;
   };
   
   // Throughput metrics (bytes per second)