SwitchDeviceClass only ever supported 'outlet'/'switch', not 'lock'.
switch.py passes desc.device_class straight to SwitchDeviceClass(...),
so any board with these hrefs raised ValueError during switch platform
setup and lost every switch entity for the device, not just the lock
ones (issue #349, TP2X_WATERPURIFIER_20K).
KIDS_LOCK_GENERIC/_VS_FALLBACK dodged this same bug (issues #181/#183)
by moving to a read-only BinarySensorDesc, but the water-purifier and
cooktop locks are genuinely writable, so they stay SwitchDesc and just
drop the invalid device_class (with an mdi:lock icon standing in for
the one entity_category=config gave them for free).
Added a registry-wide test that instantiates SwitchDeviceClass for
every SwitchDesc.device_class across every by_type registry, so a
future capability can't reintroduce the same crash.
