Add the second validateDateRange predicate mirroring
chk_meta_date_end_only_for_range, so a direct API client that sets an end
date without RANGE precision gets a clean 400 INVALID_DATE_RANGE instead of
a 500 (AC6). Shares the code with the end-before-start branch.
Also fix updateDocument_preservesStoredPrecision_whenDtoOmitsIt: its stored
fixture (MONTH + end date) is a state the DB CHECK forbids, so the
carried-over-state guard correctly rejects it. Switched to RANGE + end —
the only DB-valid non-null-end combo — preserving the test's intent.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
73f614bc3a