itinerary: move Silicon Valley and Golden Gate sunset to Sep 20

Claude-Session: https://claude.ai/code/session_01SQPbfX7jyTALGYxJw36hbT

sf_sights.md

@@ -37,7 +37,7 @@
 
 - **Apple Park Visitor Center** — Cupertino; rooftop view of the ring, AR model, store. Campus itself is closed to the public
 - **Google Visitor Experience** — Mountain View; store, café, Android statues
-- ~~**Computer History Museum**~~ — Mountain View; closed Mon–Tue, doesn't fit our car day. ❌ Skipped
+- **Computer History Museum** — Mountain View; Wed–Sun 10 AM–5 PM, closed Mon–Tue. Fits Sun Sep 20 only
 - **Stanford campus** — Palo Alto; Hoover Tower view
 
 ## Mission / Castro