Fix usage logging dedupe and reduce stats churn

- batch console log buffer events and support batched SSE log messages
- debounce usage stats update/pending events to reduce UI/runtime churn
- avoid awaiting request-success bookkeeping before returning provider responses
- deduplicate identical usage writes in usageHistory/daily aggregates
- reduce default logger verbosity from DEBUG to INFO (overridable via LOG_LEVEL)

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/handlers/chatCore/nonStreamingHandler.js

@@ -167,7 +167,13 @@ export async function handleNonStreamingResponse({ providerResponse, provider, m
   }
 
   reqLogger.logProviderResponse(providerResponse.status, providerResponse.statusText, providerResponse.headers, responseBody);
-  if (onRequestSuccess) await onRequestSuccess();
+  if (onRequestSuccess) {
+    Promise.resolve()
+      .then(onRequestSuccess)
+      .catch(err => {
+        console.error("[ChatCore] onRequestSuccess failed:", err?.message || err);
+      });
+  }
 
   // Decloak tool_use names once on raw Claude body, before any translation (INPUT side)
   responseBody = decloakToolNames(responseBody, toolNameMap);