ci(ariadne): rebuild missing base image in pipeline

Jenkinsfile

@@ -298,6 +298,22 @@ printf '%s\n' "${gate_rc}" > build/quality-gate.rc
       }
     }
 
+    stage('Build & push base image') {
+      steps {
+        container('builder') {
+          sh '''
+            set -euo pipefail
+            docker buildx build \
+              --platform linux/arm64 \
+              --file Dockerfile.base \
+              --tag "${REGISTRY}/ariadne-base:py312" \
+              --push \
+              .
+          '''
+        }
+      }
+    }
+
     stage('Build & push image') {
       steps {
         container('builder') {