#815 Fix demo apps hello_world.wait_for_approval + notification_hub.send_alert_and_wait: broken wait_for_event calls (#agentic)

Both call ctx.wait_for_event with the wrong signature: hello_world passes (step_name, timeout=timeout_seconds) - MISSING event_name; notification_hub similar. SDK sig is wait_for_event(step_name, event_name, timeout_seconds). #813 added a timeout= alias but these also omit event_name. Fix the example source (enterprise/apps/examples/{hello_world,notification_hub}.py) + republish/upgrade so the installed versions work. Surfaced during #812/#813/#814.