Four kanban dashboard test failures, all from PR salvages that picked up
the test additions but dropped the corresponding implementations.
- BOARD_COLUMNS: add 'review' (status added by PR f55d94a1e but the
board API never grew the column → test_board_empty failed because
VALID_STATUSES - {archived} mismatched the rendered columns).
- update_task: enrich the 'ready' 409 detail with the blocking parent
list (id, title, status) and add _parents_blocking_ready helper.
Implementation lost in the #26744 salvage (commit e215558ba) which
pinned the test but not the server-side code.
- dist/index.js: add parseApiErrorMessage helper, wire it through the
drag/drop banner, add patchErr state to the TaskDrawer and surface
it inline by the action row. Lost in the same #26744 salvage.
- test_diagnostics_endpoint_severity_filter: update to at-or-above
semantics (PR a94ddd807 changed the filter from exact-match so the
warning filter now correctly includes error+critical too).
362ef912ea