build(opax-mcp): add build-only Cloud Build pipeline

cloudbuild.build-only.yaml

@@ -0,0 +1,22 @@
+# cloudbuild.build-only.yaml - Bygger og pusher opax-mcp-imaget uten å deploye.
+steps:
+  # Steg 1: Bygg og tag bildet med unik $BUILD_ID
+  - name: 'gcr.io/cloud-builders/docker'
+    id: build
+    args:
+      - 'build'
+      - '-f'
+      - 'opax-mcp/Dockerfile'
+      - '-t'
+      - '${_REGION}-docker.pkg.dev/${PROJECT_ID}/${_ARTIFACT_REPO}/opax-mcp:$BUILD_ID'
+      - '.'
+
+  # Steg 2: Push det unike imaget til Artifact Registry
+  - name: 'gcr.io/cloud-builders/docker'
+    id: push
+    args: ['push', '${_REGION}-docker.pkg.dev/${PROJECT_ID}/${_ARTIFACT_REPO}/opax-mcp:$BUILD_ID']
+    waitFor: ['build']
+
+substitutions:
+  _REGION: us-central1
+  _ARTIFACT_REPO: osvauco-repo