docs(csm): Add Ownership Agent guide page

[lucasdmaley]

Summary

• Adds a new guide page for the Ownership Agent at content/en/security/cloud_security_management/guide/frontier_group/ownership_agent.md
• Covers the four topics Filipe requested for onboarding frontier partners: data sources (with priority order), supported resource types, correction UX and its impact on evaluation, and explorer query syntax for filtering by inferred owner

Reviewer notes

This is a companion to the existing ownership_preferences.md page. The file lives under frontier_group/ to match the URL structure of the published ownership preferences page.

A few areas where Filipe or the docs team should validate before merge:

• Explorer query facet names: the @ownership.owner_handle, @ownership.status, etc. facet names are inferred from the API data model. If the UI uses different facet names, please update the table in the "Query ownership in the explorer" section.
• Resource type list: the host_image row may need to be removed or renamed depending on what the UI surfaces by the time this ships.
• Auto-persist threshold: documented as 0.85 based on the RFC. Confirm this matches the shipped value.

Further reading

• Source context: filipe.teixeira-claude-context/ownership/CONTEXT.md
• Existing ownership preferences page: https://docs.datadoghq.com/security/cloud_security_management/guide/frontier_group/ownership_preferences/
• Frontier group page: https://docs.datadoghq.com/security/cloud_security_management/guide/frontier_group/

Made with Cursor

[maycmlee]

Created DOCS-14390 for review.

[lucasdmaley]

Superseded by #36695 (branch was accidentally cut from a non-master branch)