fix: Cloud 401/404 and empty lists should be readable

[margaretjgu]

cloud_api_error dumps the raw body (Cloud API error 404: {"errors":[…]}). Empty list returns [] with no hint.

• Parse errors[].message (and code if present) into error.message
• 401/403: name Cloud API key vs project ES key confusion, plus the console API keys URL
• 404 on a project/deployment: name list for that product line
• Empty list on projects * list / list-deployments: stderr one-liner with the matching create command (stdout stays [] under --json)

Do not replace #636. This is Cloud body shape and empty-account UX.

Acceptance: mock 404 with {"errors":[{"message":"project not found"}]} prints that message, not the raw JSON blob. Empty list with --json is still []. Human mode prints the create hint on stderr.