Improve comments for property setters in ZNPCoordinator

Co-authored-by: puddly <32534428+puddly@users.noreply.github.com>

Author: Copilot

zigpy_znp/zigbee/device.py

@@ -21,15 +21,19 @@ def manufacturer(self) -> str:
 
     @manufacturer.setter
     def manufacturer(self, value: str) -> None:
-        pass  # Read-only for coordinator
+        # Setter required to match parent class interface (which has read-write properties)
+        # but intentionally does nothing since coordinator manufacturer is hardware-determined
+        pass
 
     @property
     def model(self) -> str:
         return "Coordinator"
 
     @model.setter
     def model(self, value: str) -> None:
-        pass  # Read-only for coordinator
+        # Setter required to match parent class interface (which has read-write properties)
+        # but intentionally does nothing since coordinator model is hardware-determined
+        pass
 
     async def request(
         self,