Remove key_fn from Capability — pattern cap keys are now always derived
automatically: strip digits from href segments, join with '_', append
'_' + desc.key. /door/cooler/0 + 'open' -> door_cooler_open.
DOOR_GENERIC entity key: 'open' (not 'door_open'). Remove _door_key helper.
Fridge registry: DOOR_FRIDGE/DOOR_FREEZER replaced by DOOR_GENERIC pattern cap.
Golden baseline: door_fridge_open -> door_cooler_open.
Move device dumps to tests/fixtures/dumps/ (tracked) so tests run in CI
without local-tools/ dependencies.
Marc Billow