transport: add SIXT SFO rental

expenses.md

@@ -22,7 +22,8 @@ Tricount's default currency is USD. Shared expenses are split 50/50 between **KT
 | Accommodation | Los Angeles — DTLA Airbnb | US$860.00 | KTVT | Shared 50/50 | [`airbnb-la-dtla.md`](bookings/stays/airbnb-la-dtla.md) |
 | Accommodation | Las Vegas — Wyndham Desert Rose | US$630.00 | KTVT | Shared 50/50 | [`wyndham-desert-rose-las-vegas.md`](bookings/stays/wyndham-desert-rose-las-vegas.md) |
 | Flights | MS & LK — YVR ↔ SFO | CA$1,369.76 | LKMS | Couple-only: LKMS | [`flights-ms.md`](bookings/transport/flights-ms.md) |
+| Car rental | SIXT — SFO round trip | US$897.93 | LKMS | Shared 50/50 | [`car-rental.md`](bookings/transport/car-rental.md) |
 
 ## Settlement
 
-**KTVT owes LKMS US$485.26.**
+**KTVT owes LKMS US$934.22.**