P0: replace `+` array union with array_merge() in
Settings_Fields_Extended::get_fields(). PHP `+` keeps left-side keys
when both arrays are integer-indexed — silently drops all 11 image fields
(indexes 0–10 collide with indexes 0–10 of the local array). array_merge()
is already the operator used by the parent class at class-settings-fields.php:84.
P1: restore `php scripts/check-constants.php --self-test` step in the
check-constants CI job. Step was present in v0.21.0 and accidentally dropped
in the CI rewrite. Script logic is intact; CI now exercises it again.
Also adds SettingsFieldsExtendedTest (3 assertions) as a regression guard:
cardinality (29 = 18 local + 11 image), presence check, and per-field
id/section contract. If a + union ever re-appears, test_get_fields_returns_29_fields
fails with a message naming the root cause.
Agent-Session: engineer-infra-prab-p0fix-20260616
Board submenu now registers at admin_menu priority 11 (parent toplevel at 10)
so the page hook lands under prautoblogger_page_prautoblogger-board; $submenu
reordered defensively to keep Board the first item / top-level click target.
Enqueue gate now matches; board.css/board.js load for the first time on prod.
Regression test: BoardMenuRegistrationTest (fails on pre-fix main).
QA: APPROVE-W-P2 qa-reviews/prautoblogger/2026-06-12-6168520.md
Thread: convo/prautoblogger/threads/2026-06-pipeline-v2-phase2-admin/ seq 11-14
Agent-Session: cto-board-404-hotfix-merge-20260612
