Per the Prisma Cloud scan workflow: verify registry login, registry URL, and tag before re-running the scan.

Context: Problem: The CI scan step fails before scanning starts, at image pull. Common causes: missing registry authentication (add a login step before the scan); the image_registry input does not match the actual registry URL; the image_tag is wrong or the tag does not exist; the runner cannot reach the registry (network). Verify each in order before re-running - the action surfaces which of these it hit.

## Matched source
Source: Source: https://github.com/solacedev/solace-public-workflows/blob/HEAD/prisma-cloud-scan/README.md
Original query: "Prisma Cloud twistcli scan fails pulling the image - check registry auth, URL, and tag"
Key terms: auth, check, cloud, fails, image, prisma, pulling, registry, scan, twistcli