Start Agent Builder chat from a dashboard

## Summary

Dashboard authors with Agent Builder access can now start chat from two places in the dashboard editor. An empty dashboard offers editable prompt suggestions such as Create a dashboard for my metrics and Monitor my logs, while the Add panel flyout offers Create with chat; each option opens a new conversation without sending the prompt automatically.

**Why this needs docs:** The PR adds visible dashboard creation entry points and a new workflow that the current dashboard and Agent Builder pages do not identify.

## Resources

- PR [#278142](https://github.com/elastic/kibana/pull/278142) — [Dashboard] Add Chat entry points for dashboard creation

Screenshots from PR


## Availability

| Channel | Details |
|---------|---------|
| **Stack** | v9.6.0 |
| **Serverless** | Aug 10–Aug 14 |
| **Feature flag** | None — active by default |

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*Created with [Docs Quest Scanner](https://github.com/florent-leborgne/docs-quest-scanner) by @florent-leborgne*

## Suggested edits

[Create a dashboard from the Kibana UI](https://www.elastic.co/docs/explore-analyze/dashboards/create-dashboard) > Create a dashboard with Elastic Agent Builder
- **What the docs say:** You can also create dashboards through natural language chat with Elastic Agent Builder agents. Describe what you want to visualize and the agent builds a dashboard with ES|QL-powered visualization panels.
- **What to add:** Extend the existing workflow to explain that users with Agent Builder access can select a prompt or Open chat on an empty dashboard, or select Add panel, then Create with chat; note that a selected prompt opens an editable draft and is not sent automatically. Applies from 9.6.0 and in serverless.