Home Assistant calls turn_on regardless of current state, and applying a
scene re-asserts every captured state, so asserting the alarm on over a
rinse-only AddWashSet_1 rewrote it to _7 -- silently widening the moments
the user picked, with no state change on this switch to point at it. The
write is now refused when the mask is already non-zero.
Distinct from the off-then-on path documented in _add_wash_bit_switch,
where the appliance has no subset left to keep.
Also satisfies the ty check on the new tests: resolve(),
for_device_by_model() and exists_fn are all optional, asserted the way
the other capability tests do.
The master alarm switch wrote AddWashSet_7/_0 without consulting
_add_wash_mask, so a device reporting a wider mask (AddWashSet_15) or a
non-numeric one had it truncated to three bits -- the write that mask's
own docstring rules out, while the per-moment switches already refused it.
Also corrects the washer_ww6500 golden docstring: the fixture carries no
/oic/d and the test passes no device_types, so the device is typed solely
by the WW consumer prefix in its description. A51 is not a board token,
which makes that the fragile route worth naming.
Marek Tyburec