As a PA modifying an approved booking I want a changed service request to clear its approval and return to its approvers.

[nopivnick]

This was generated by AI during triage.

Split out of #1596 during triage.

Why

The modification endpoint (PA/admin, for APPROVED and WALK_IN bookings) copies all seven *ServiceApproved flags forward unchanged and forces the machine into the Approved state. A service request that was changed during modification keeps its old service decision, and a newly requested service has no decision at all and is never routed to its approvers. Approvers never hear about the change.

Desired behavior

• Modifying an approved service request clears that service's decision and routes it to the appropriate service approver(s).
• A service counts as changed when any field in its section changed on any room: toggle or choice, detail text, or chartfield, in the per-room maps or the legacy flat fields (same rule as As a User editing a booking I want the Services step to show which services are already approved. #1596).
• Unchanged services keep their decisions.
• The Services step in modification context already shows decision marks once As a User editing a booking I want the Services step to show which services are already approved. #1596 lands; this ticket only changes what happens on submit.

Open questions (to settle at triage)

• What the booking-level state is while a re-routed service is pending. Today modification forces Approved; a pending service may need the booking back in Services Request, or an approved booking with one pending service.
• Whether a newly added service (not previously requested) routes the same way as a changed one.
• Which notification the service approvers receive, and whether the requester is told the service is pending again.

Depends on

• As a User editing a booking I want the Services step to show which services are already approved. #1596 (change detection per service key, and the machine honoring already-decided services when re-entering Services Request)