[Admin UI extensions 2025-10]: IA for Target APIs and components

[mcvinci]

This PR:

• Revises the 2025-10 IA for Target APIs and components to align with Admin UI extensions V2
• Partially closes https://github.com/Shopify/shopify-dev/issues/66225
• Relates to https://github.com/Shopify/shopify-dev/pull/66616

[github-actions]

We detected some changes in packages/*/package.json or packages/*/src, and there are no updates in the .changeset directory. If the changes are user-facing and should cause a version bump, run yarn changeset to track your changes and include them in the next release CHANGELOG. If you are making simple updates to repo configuration, examples, or documentation, you do not need to add a changeset.