parse_jobsel() parses c-a-ts-seq with an optional [k] or [a-b] under a
fixed grammar and check order (syntax, field widths, array-identity
alignment, element bound, reversed range), saturating digits so an
oversized number cannot wrap; plus is_array_tag(), jobsel_element_id(),
jobsel_strerror() and JOBID_FIELD_MAX_* constants. The selection-cases
conformance table runs in the libxce suite.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>