perf: add HTTP connection pooling across providers and disable proxy buffering on SSE streams

internal/providers/grok.go

@@ -20,7 +20,7 @@ type GrokProvider struct {
 
 func NewGrokProvider(cfg config.GrokConfig, apiKey string) *GrokProvider {
 	return &GrokProvider{
-		client: resty.New().SetTimeout(10 * time.Minute),
+		client: NewOptimizedRestyClient(10 * time.Minute),
 		config: cfg,
 		apiKey: apiKey,
 	}