-- Planning Schedule — add original_hours column
-- Stores the baseline planned hours from the first Calc run.
-- Preserved across subsequent re-calcs so the delta badge can show
-- how actual scheduling compares to the original plan.
-- Created: 2026-04-07
-- NOTE: applied via planning_migrate.php (planningEnsureOriginalHoursColumn)
-- to support MySQL versions that lack ADD COLUMN IF NOT EXISTS syntax.
