fix(pipeline): harden upstream resilience and production shutdown

DoH через DoWithRetry; CDN preview через UpstreamHTTPDo; частичный fail CDN (EVOBGP_CDN_PARTIAL_OK); безопасный доступ к Job.Meta; drain jobs при SIGTERM; ValidateProductionEnforce при EVOBGP_PRODUCTION=1.

Co-authored-by: Cursor <[email protected]>

internal/pipeline/upstream_http.go

@@ -8,6 +8,11 @@ import (
 	"evobgp/internal/httpclient"
 )
 
+// UpstreamHTTPDo performs an outbound GET/POST with circuit breaker + retries (CDN, previews).
+func UpstreamHTTPDo(ctx context.Context, hc *http.Client, req *http.Request) (*http.Response, error) {
+	return upstreamHTTPDo(ctx, hc, req)
+}
+
 func upstreamHTTPDo(ctx context.Context, hc *http.Client, req *http.Request) (*http.Response, error) {
 	if hc == nil {
 		hc = httpclient.New(httpclient.DefaultTimeout)