Follow-up work deferred from PR #27875 (RUN-3836) for podman machine os-apply bootc implementation.

This story covers two main areas:

1. 1. Transport Support - Add support for containers-storage transport to allow using local images. The bootc command uses --transport flags rather than URI schemes. Need to determine whether to mirror bootc's approach or extend existing podman URI patterns.

2. Documentation Updates - Update man pages to reflect the transition from rpm-ostree to bootc for the podman machine os apply command.

Related PR: https://github.com/containers/podman/pull/27875

Acceptance Criteria

This should be filled in by the assignee prior to the card going to code review and preferably earlier.

• [ ] containers-storage transport support implemented for os apply
• [ ] Design decision made on transport flag approach (bootc-style vs podman URI style)
• [ ] Man pages updated to document bootc usage