Implement scope-aware Form, UserControl, and component activation

## Objective

Implement approved activation and scope behavior for common UI lifetimes, including modal and modeless Forms, nested UserControls, components, factories/navigation, disposal ordering, and failure cleanup. Do not introduce a process-wide static service locator.

## Completion guidance

- Keep the implementation focused on the objective while allowing the assignee to improve the approach based on research.
- Document important decisions, rejected alternatives, dependencies, and follow-up work.
- Add or update tests and documentation appropriate to the work.
- Verify locally and in CI where the task changes code or generated artifacts.

No files, tests, or entry points are named. Start by researching the approved activation and scope behavior for Forms, UserControls, components, factories, and navigation in the repository; done means the behavior, disposal and failure cleanup are implemented with appropriate tests and documentation.

Written by the indexing model from the issue text.