fix(models): add missing creation_time initialization in Zone class

The Zone class declared creation_time as an attribute but never
initialized it in __init__, causing AttributeError when accessed.

Also fixes type annotations to match API reality (int timestamps)
and aligns with the Place class pattern.

Author: tetienne

pyoverkiz/models.py

@@ -885,8 +885,8 @@ class ZoneItem:
 class Zone:
     """A Zone groups related devices inside a place."""
 
-    creation_time: str
-    last_update_time: str
+    creation_time: int
+    last_update_time: int | None = None
     label: str
     type: int
     items: list[ZoneItem] | None
@@ -897,7 +897,8 @@ class Zone:
     def __init__(
         self,
         *,
-        last_update_time: str,
+        creation_time: int,
+        last_update_time: int | None = None,
         label: str,
         type: int,
         items: list[dict[str, Any]] | None,
@@ -907,6 +908,7 @@ def __init__(
         **_: Any,
     ) -> None:
         """Initialize Zone from API data and convert nested items."""
+        self.creation_time = creation_time
         self.last_update_time = last_update_time
         self.label = label
         self.type = type