0.9.5

• Fix KeyError: 'entities' in button.py (own async_added_to_hass override was missed in 0.9.4)
• Defensive .get() for optional config fields (icon, icon_on, entity_name, model) to prevent KeyError
• Replace deprecated device_registry.async_get_device with async_get_device_by_identifier
• Coerce all device registry text fields (manufacturer, name, model, sw_version) to string