itinerary: split day plans into days/, plan SF Sep 21

- One file per day under days/; timeline table reduced to date, weekday, place
- Sep 19–20: KT & VT Uber to Airbnb, rest day; LK & MS drive rental to Airbnb
- Sep 21: Silicon Valley morning, optional Twin Peaks / Painted Ladies /
  Lands End, Battery Spencer at sunset
- LK Hertz LAX rental marked not available for planning; LA / San Diego
  hotels cancelled
- sf_sights: add Silicon Valley and Mission / Castro, skip Computer History
  Museum

Claude-Session: https://claude.ai/code/session_01CWLR7htYGAB9i89P8jCCLn

bookings/transport/car-rental-lk-los-angeles.md

@@ -1,5 +1,7 @@
 # Car Rental — LK in Los Angeles
 
+⚠️ **Do not plan around this car (2026-09-12).** LK cancelled her LA (Sep 25) and San Diego (Sep 26) hotels; the rental is expected to be cancelled as well. Kept here for the record until LK confirms.
+
 ✅ **Booked 2026-09-04 through Expedia — itinerary `73537324893669` · Hertz confirmation `L701E988AD2`**
 ([confirmation email](../../sources/transport/Expedia_Hertz_LAX_Sep25-27_73537324893669.eml))