Components.AI: Make approvals and reasoning disclosures accessible

### Is your feature request related to a problem? Please describe the problem.

Approval requests and reasoning disclosures lack complete announcement, labeling, status, and focus behavior.

### Describe the solution you'd like

Make each approval a labeled non-modal region that announces once, receives initial focus without trapping it, names the tool and target in each decision, leaves an accessible decision record, and handles Stop as cancellation. Correct `` labeling and state announcement for reasoning content.

### Additional context

Leaf task for #68227 requirements I6-I7 and the approval structural sketch.

Start with the Components.AI entry points and the approval structural sketch referenced by parent issue #68227, focusing on requirements I6-I7. Verify the approval and reasoning flows against the stated announcement, labeling, focus, decision-record, cancellation, and details-state behaviors; done means each listed accessibility behavior is implemented and testable.

Written by the indexing model from the issue text.