Event-driven workflow triggers

**What the feature is (as Title)**

Event-driven workflow triggers

**Value proposition**

Workflows can run the moment something happens in the platform instead of waiting on a schedule or a manual run. Event-driven triggers let workflows respond to lifecycle events across Elastic solutions, such as a case being updated or a new stream appearing, with solution teams able to expose their own domain events as triggers. This turns Workflows into a real-time automation layer: the event happens, the right workflow fires, no polling and no lag.

**Expected outcome**

Event-driven triggers move to General Availability:

- Workflows can subscribe to platform and solution lifecycle events
- A growing trigger registry as solution teams expose domain events
- Production-ready reliability for event-triggered execution

**Optional: Key user stories / use cases**

- Firing a notification and sync workflow the moment a case changes state
- Reacting to new data streams with onboarding automation