Add per-leg sights menus; rename yosemite_sights to parks_sights

- Rename yosemite_sights.md -> parks_sights.md, broaden to cover both
  Yosemite and Sequoia/Kings Canyon
- Add sf_sights.md, la_sights.md, vegas_sights.md candidate menus
- Link all sights menus from README and itinerary

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

vegas_sights.md

@@ -0,0 +1,29 @@
+# Las Vegas — Places to See
+
+*Candidate menu of sights. No day plan yet (Sep 30–Oct 3) — pick from here to build one.*
+
+> **No car in Vegas:** the rental is dropped at LAX on Sep 30 before flying in. Getting around the Strip is walkable + rideshare/monorail, but **any day trip (Grand Canyon, Hoover Dam, etc.) needs a tour or a separate Vegas rental** — plan that ahead.
+
+## The Strip
+
+- **Bellagio Fountains** — free water show, every 15–30 min
+- **Hotel-hopping** — Venetian, Caesars, Bellagio conservatory, etc.
+- **High Roller** — observation wheel at The LINQ
+- **Sphere** — shows + exterior display
+
+## Old Vegas
+
+- **Fremont Street Experience** — light canopy, downtown vibe
+
+## Shows & Entertainment
+
+- **Cirque du Soleil** residencies (O, Mystère, etc.)
+- Headliner residencies — book ahead
+
+## Day trips (need tour or rental)
+
+- **Hoover Dam** — ~45 min
+- **Red Rock Canyon** — ~30 min, scenic loop drive
+- **Valley of Fire State Park** — ~1 hr, red sandstone
+- **Grand Canyon (West / South Rim)** — long day, ~2–4.5 hrs each way
+- **Death Valley** — ~2 hrs, extreme heat in early Oct