drone yaml add cosign login

.drone.yml

@@ -63,17 +63,25 @@ steps:
         from_secret: COSIGN_KEY
       COSIGN_PASSWORD:
         from_secret: COSIGN_PASSWORD
-      IMAGE_DIGEST:
-        from_secret: IMAGE_DIGEST  # Optional – oder aus export-env
+      REGISTRY_URL:
+        from_secret: REGISTRY_URL
+      DOCKER_USER:
+        from_secret: DOCKER_USER
+      DOCKER_PASS:
+        from_secret: DOCKER_PASS
     commands:
       - echo "=== 🔏 Installing Cosign v3.0.2 ==="
       - . build.env
       - apk add --no-cache curl ca-certificates
       - curl -sSL -o /usr/local/bin/cosign https://github.com/sigstore/cosign/releases/download/v3.0.2/cosign-linux-amd64
       - chmod +x /usr/local/bin/cosign
+      - cosign version
+
+      - echo "=== 🔐 Logging in to registry for signing ==="
+      - cosign version
+      - echo "$DOCKER_PASS" | cosign login --username "$DOCKER_USER" --password-stdin "$REGISTRY_URL"
 
       - echo "=== 🔏 Signing Image ==="
-      - cosign version
       - cosign sign --yes --key env://COSIGN_KEY "$IMAGE_DIGEST"
       - echo "✅ Image signed successfully."
     depends_on: