[Search][Getting Started] AI assisted onboarding CTA (elastic#255192)

## Summary
- create sample agent files and context: e.g.
https://github.com/kevinsweet/elastic-ide-context/tree/main
- make a prompt that points an LLM to that context
- add an interface in kibana for users to add the prompt to cursor,
claude, or use in agent builder

## Changes
- new shared package `@kbn/search-agent` containing markdown files and
script that generate TS files for agent builder registration.
- `agent_install.tsx` - section on getting started page. Asks users
about their use case and their dev environment
- `prompt_modal.tsx`- Displays the prompt for users to copy into their
CLI
- `register_search_agent` - adds skills and a new "Elasticsearch
Onboarding Agent" in agent builder

## Screenshots:

### Video Demo
- [google drive
link](https://drive.google.com/file/d/1qM27hvwXQGgwAf1cHPTQD0cXVFn230GP/view?usp=sharing)

### Getting started page

<kbd><img width="500" height="542" alt="Screenshot 2026-02-27 at 10 06
09 AM"
src="https://github.com/user-attachments/assets/080bfe31-3abb-40f6-8c9a-33d34f119de8"
/></kbd>

### Cursor


<kbd>
<img width="863" height="565" alt="image"
src="https://github.com/user-attachments/assets/fef152a9-ad8a-471d-8f19-0b6587f7ecae"
/>
</kbd>


### Claude
<kbd>
<img width="863" height="565" alt="image"
src="https://github.com/user-attachments/assets/9dca55b8-b2bb-4b9a-a5b4-a4095eb04e6f"
/>
</kbd>

### Agent Builder
<img width="500" height="908" alt="Screenshot 2026-02-27 at 10 04 56 AM"
src="https://github.com/user-attachments/assets/abb7e3bf-041d-4483-bb18-28df96694bbf"
/>

## Telemetry
Added data test subjects for various click actions:
agent_install.tsx:
- `useCase-option-${id}` — each use case dropdown option (e.g.
`useCase-option-general-search`)
- `agentInstallUseCaseSelect`        — the use case selector
- `agentInstallLaunchBtn`            — the "Open in..." button
- `agentInstallOpenInCursor`        — Cursor menu item
- `agentInstallOpenInClaudeCli`     — Claude / CLI menu item
- `agentInstallOpenInAgentBuilder`  — Kibana Agent Builder menu item

prompt_modal.tsx:
- `promptModalCloseBtn` — the Close button
- `promptModalCopyBtn`  — the Copy to clipboard button

### Checklist

Check the PR satisfies following conditions. 

Reviewers should verify this PR satisfies this list as well.

- [x] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/src/platform/packages/shared/kbn-i18n/README.md)
- [ ]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios
- [ ] ~If a plugin configuration key changed, check if it needs to be
allowlisted in the cloud and added to the [docker
list](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)~
- [ ] ~This was checked for breaking HTTP API changes, and any breaking
changes have been approved by the breaking-change committee. The
`release_note:breaking` label should be applied in these situations.~
- [ ] [Flaky Test
Runner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1) was
used on any tests changed
- [x] The PR description includes the appropriate Release Notes section,
and the correct `release_note:*` label is applied per the
[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)
- [x] Review the [backport
guidelines](https://docs.google.com/document/d/1VyN5k91e5OVumlc0Gb9RPa3h1ewuPE705nRtioPiTvY/edit?usp=sharing)
and apply applicable `backport:*` labels.

## Release Note

Adds AI assistant led onboarding option to the Elasticsearch getting
started page.

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Happy <yesreply@happy.engineering>
Co-authored-by: Rodney Norris <rodney.norris@elastic.co>
Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>
Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

Author: 6 people

.github/CODEOWNERS

@@ -623,6 +623,7 @@ src/platform/packages/shared/kbn-safer-lodash-set @elastic/kibana-security
 src/platform/packages/shared/kbn-saved-search-component @elastic/obs-exploration-team
 src/platform/packages/shared/kbn-scout @elastic/appex-qa
 src/platform/packages/shared/kbn-scout-synthtrace @elastic/appex-qa
+src/platform/packages/shared/kbn-search-agent @elastic/search-kibana
 src/platform/packages/shared/kbn-search-api-panels @elastic/search-kibana
 src/platform/packages/shared/kbn-search-connectors @elastic/search-kibana
 src/platform/packages/shared/kbn-search-errors @elastic/kibana-data-discovery

package.json

@@ -986,6 +986,7 @@
     "@kbn/screenshotting-example-plugin": "link:x-pack/examples/screenshotting_example",
     "@kbn/screenshotting-plugin": "link:x-pack/platform/plugins/shared/screenshotting",
     "@kbn/screenshotting-server": "link:src/platform/packages/private/kbn-screenshotting-server",
+    "@kbn/search-agent": "link:src/platform/packages/shared/kbn-search-agent",
     "@kbn/search-api-keys-components": "link:x-pack/solutions/search/packages/kbn-search-api-keys-components",
     "@kbn/search-api-keys-server": "link:x-pack/solutions/search/packages/kbn-search-api-keys-server",
     "@kbn/search-api-panels": "link:src/platform/packages/shared/kbn-search-api-panels",