docs(migration): add OSGi → Cloud Manager reference and wire migration skill

[Himanich]

OSGi → Cloud Manager reference and wire migration skill

Description

Adds a dedicated reference for moving OSGi configuration toward AEM as a Cloud Service patterns: scanning ui.config / .cfg.json, using $[secret:] / $[env:], and aligning with Cloud Manager environment variables—without pulling Java BPA pattern work into the same session.

Updates the AEM Cloud Service migration skill so agents auto-read the new reference when users ask to scan configs or set up Cloud Manager secrets/variables, and splits Branch A (OSGi → Cloud Manager) from Branch B (Java/HTL/BPA pattern migration).

Related Issue

Motivation and Context

Customers migrating to AEM CS need repeatable agent guidance for secrets and environment-specific values in OSGi config that complements the existing BPA/CAM Java migration flows, without conflating those with a BPA pattern id.

How Has This Been Tested?

open the migration skill in an agent and run the starter prompt: "Scan my config files and create Cloud Manager environment secrets or variables." — verify the agent loads references/osgi-cfg-json-cloud-manager.md and follows the phased workflow.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.