resolve()/for_device_by_model() return DeviceRegistry | None; four new
test files used reg.capabilities/reg.pattern_capabilities without
narrowing away None first. Add the same 'assert reg is not None' idiom
test_dehumidifier_tp1x_dhm01001_capabilities.py already uses.
Verified against a clean venv running the exact CI commands (ruff format
--check, ruff check, ty check, pytest) rather than trusting a stale local
venv that had picked up a mismatched python3.11/3.13 site-packages split.
/diagnosis/vs/0 was the dump's only unbound href, now covered via
dishwasher.DIAGNOSIS (same shape already reused by airconditioner.py).
This steam-oven-class board's /mode/vs/0 options[] carries no UpperLamp_
token at all, unlike the NV7000BS-class board LAMP was proven against --
LAMP had no exists_fn, so it registered anyway, always read Off, and any
write to it was a no-op the device had no reason to honor. Gives it the
same options-token exists_fn gate issue #183 already added to
fast_preheat/natural_steam/energy_saving/cooktop_on_alert.
Marc Billow