docs: add TODO list and settle 2026 park entry rules

Collect the open action items scattered across booking records into
TODO.md, starting with the US$250 nonresident annual pass. Yosemite has
no timed-entry reservation in 2026, and per NPS one nonresident pass
admits the whole vehicle and waives the per-person surcharge at both
parks, so update the parks notes accordingly.

TODO.md

@@ -0,0 +1,34 @@
+# TODO
+
+Open items before and during the trip. Tick and date when done.
+
+## Before departure (Sep 19/20)
+
+- [ ] **Buy the US$250 nonresident annual pass** — digital, on
+  [recreation.gov](https://www.recreation.gov/pass/annual), before the Sep 22
+  Yosemite entrance. One pass admits the whole car at Yosemite and
+  Sequoia/Kings Canyon and waives the US$100/person nonresident surcharge.
+  Without it: ~US$435 per park, US$870 total. Pass holder must be in the
+  car with photo ID at every gate.
+- [ ] **KT: complete the LA DTLA online check-in form** —
+  [Hostaway portal](https://guest-portal.hostaway.com/65596088/dxYlP4ov/check-in).
+  Entry code is activated only after it's submitted.
+- [ ] **MS: assign Air Canada seats** for the YVR ↔ SFO flights.
+  See [`flights-ms.md`](bookings/transport/flights-ms.md).
+- [ ] **LK: confirm Budget LAX pickup/return location and price** —
+  itinerary `73544810702403`. Hertz cancellation refund also TBC.
+- [ ] **Brand Plaza Glendale** room, price and payment TBC.
+- [ ] **Oct 3 overnight stop** on the drive back to SFO — not yet chosen.
+
+## Money
+
+- [ ] **Watch Visa 3924 for the US$228.43 Gilmore Cabin refund** after the
+  Sep 16 date change. Then update the payment row in
+  [`cabin-sequoia-miramonte.md`](bookings/stays/cabin-sequoia-miramonte.md).
+
+## During the trip
+
+- [ ] **Sep 23: screenshot the Miramonte door code** while there's signal —
+  it arrives 24 h before the Sep 24 check-in; the cabin has no service.
+- [ ] **Sep 22: save the Yosemite door code 0517 and wifi offline** before
+  leaving cell coverage.