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_capability.py

@@ -1,5 +1,5 @@
-from samsung_appliance.registry.capability import Capability
-from samsung_appliance.registry.entities import BinarySensorDesc
+from custom_components.localthings.ocf.registry.capability import Capability
+from custom_components.localthings.ocf.registry.entities import BinarySensorDesc
 
 
 def test_capability_defaults():