Fix isCustomTeamDefaultValue type guard to check all required properties (#3315)

* Fix isCustomTeamDefaultValue type guard to check all required properties

The type guard was only checking for 'defaultValue' and 'teamDefaultValue'
properties, allowing objects missing 'owner' and 'expirationDate' to pass
the check. This caused runtime errors when accessing expirationDate on
incomplete objects.

Now checks for all four required properties of CustomTeamDefaultValue<T>.

* chat-lib: update package to match main package.json