DVH Refund & Driver Handover Fixes

This is a pre-agreed fixed milestone for an existing developer who has already reviewed the DVH codebase.
Agreed baseline:
staging commit 291dfca7ec2c83c660cdfc7209f583946bf5088a
Scope
1. Fix cancellation/refund handling so the full refundable balance, including the captured £250 deposit, is correctly accounted for.
2. Fix the driver handover equipmentStatus / “Not present” issue so a legitimate missing-equipment reason survives validation and does not incorrectly block completion.
Acceptance requirements
Cancellation/refund:
- £200 hire + £250 deposit cancellation returns the correct £450.
- retries or lost responses cannot cause a second refund.
- partial prior refunds return only the outstanding refundable balance.
- Stripe failures remain recoverable.
- Stripe success followed by database failure can recover safely without losing or duplicating money.
- pending and successful refunds remain distinct.
- uncaptured-payment cancellation continues to work correctly.
Equipment handover:
- valid “Not present” plus reason is preserved and permits an otherwise valid handover.
- blank reasons and invalid statuses are rejected.
- equipment marked present still requires the appropriate photograph.
- delivery and collection must both work without weakening existing ownership, checklist, agreement or signature protections.
Deliverables
- code committed to a VOD-controlled GitHub repair branch;
- regression tests for both fixes;
- Stripe test-mode evidence;
- written handover covering commits, test results, outstanding issues and next steps.
Commercial terms
- Fixed price: £151.11
- Maximum effort: 10 hours
- Delivery: 1–2 working days
- No additional work or charges without written approval.
Testing must remain isolated and/or use Stripe test mode.
No production deployment, live payment/refund, database migration or infrastructure change is authorised under this milestone.
Subsequent DVH work will be agreed separately after this milestone is reviewed and accepted.