Review fix: validate engine keys as child ids; every-day three-child walk

Review round 1 (Codex gpt-5.6-terra, 2 LOW): engine snapshot keys now
pass _validate_child_id (True/1.0 compare equal to 1 and would be
accepted then behave differently on lookup); the always-present test
now walks all 28 days asserting all three children's expected verdicts
instead of sampling every third day. Suite: 985 passed.

custom_components/nestquest/presence.py

@@ -339,6 +339,10 @@ class PresenceEngine:
                 f"{schedules!r}"
             )
         for child_id, schedule in schedules.items():
+            # Validate the KEY as a model child id too: True and 1.0
+            # compare equal to 1, so {True: schedule(1)} would be
+            # accepted and then behave differently on lookup.
+            _validate_child_id(child_id)
             if not isinstance(schedule, PresenceSchedule):
                 raise ValueError(
                     f"schedules[{child_id!r}] must be a PresenceSchedule, "