ata-validator

One format violation reports one error. The error path turns each failing statement of a format check into an error push, and it kept going after pushing, so a single bad value collected one identical error per statement it failed: twelve for date-time on a short string, five for time, two for uuid and hostname. The check now leaves the format block on the first failure. Verdicts are unchanged; only the duplicate copies of the same error are gone. tests/test_format_single_error.js holds every built-in format to exactly one error across 25 invalid values.