feat(rustproxy-http): add protocol failure suppression, h3 fallback escalation, and protocol cache metrics exposure

ts/proxies/smart-proxy/rust-metrics-adapter.ts

@@ -1,4 +1,4 @@
-import type { IMetrics, IBackendMetrics, IThroughputData, IThroughputHistoryPoint } from './models/metrics-types.js';
+import type { IMetrics, IBackendMetrics, IProtocolCacheEntry, IThroughputData, IThroughputHistoryPoint } from './models/metrics-types.js';
 import type { RustProxyBridge } from './rust-proxy-bridge.js';
 
 /**
@@ -216,6 +216,9 @@ export class RustMetricsAdapter implements IMetrics {
       result.sort((a, b) => b.errors - a.errors);
       return result.slice(0, limit);
     },
+    detectedProtocols: (): IProtocolCacheEntry[] => {
+      return this.cache?.detectedProtocols ?? [];
+    },
   };
 
   public udp = {