refactor: move samsung_appliance/ into custom_components/localthings/ocf/

Makes the integration fully self-contained for HACS distribution.
Users installing via HACS get everything in one directory; no external
samsung_appliance package needed.

All component imports updated to relative (.ocf.*); all test imports
updated to custom_components.localthings.ocf.*. ocf_root_ca.pem moves
with the package and resolves correctly via Path(__file__).parent.

tests/test_fridge_multi_instance.py

@@ -7,9 +7,9 @@ pattern capability that auto-derives distinct keys from the href segments.
 """
 from tests.conftest import _load_resources
 
-from samsung_appliance.registry.adapter import _key
-from samsung_appliance.registry.by_type import refrigerator
-from samsung_appliance.registry.discovery import discover
+from custom_components.localthings.ocf.registry.adapter import _key
+from custom_components.localthings.ocf.registry.by_type import refrigerator
+from custom_components.localthings.ocf.registry.discovery import discover
 
 
 def test_two_doors_get_distinct_keys():