feat: add Samsung ARTIK051_REF_17K fridge-freezer descriptor

- Full resource map discovered via live CoAP-DTLS session against
  ARTIK051_REF_17K fridge-freezer (firmware DA-REF-ART-COMMON-1_20201124)
- seed_path: /device/0 (returns 32 links including hidden appliance resources)
- Entities: fridge/freezer temp + setpoints, 3x door sensors (fridge,
  freezer, convertible zone), power (W), energy (kWh, total_increasing),
  water filter usage/status, ice maker, rapid fridge/freeze, sabbath mode
- Port: 49155 (not 49154)

First known public documentation of this firmware's local CoAP-DTLS
resource layout.

samsung_appliance/appliances/__init__.py

@@ -12,11 +12,13 @@ startup; the bridge itself stays class-agnostic.
 from .base import ApplianceDescriptor
 from .dryer import DRYER
 from .oven import OVEN
+from .fridge import FRIDGE
 
 
 DESCRIPTORS: dict[str, ApplianceDescriptor] = {
     DRYER.name: DRYER,
     OVEN.name:  OVEN,
+    FRIDGE.name: FRIDGE,
 }