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

`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.