Sub-ticket of PLUTO-361 Migration policy: future SQL migrations that mutate trigger-archived tables (practicas, userRoles, users, periodos, comisiones, studentAssignments, comisionAdjuntos, comisionJtps, jtpAyudantes, accessRequests if added) must SET LOCAL app.user_id = '<system sentinel UUID>' + app.archive_reason = 'system:migration:NNN' before any INSERT/UPDATE/DELETE. Document in pluto-commons + add lint to gitpush-pre.sh. · pluto