The MCS-150 intake-completion email linked customers to /order/dot-compliance,
which is the sales/checkout page -- it ignores ?order= and asks the customer to
re-pick services and pay again, so they 'cannot enter any data' (Paul Wilson's
report). Link to the per-service intake wizard /order/<slug>?order=... instead,
which loads the paid order, pre-fills from the FMCSA census, and drops payment.
Also add a Trailers field to the DOT intake fleet section and wire it through to
the MCS-150 PDF Q26 trailer row, so carriers can update trucks AND trailers.