Implement the WinForms Blazor Hybrid composition template

## Objective

Create the supported Hybrid composition using one service provider and coherent application lifetime. Cover WebView startup/disposal, configuration, logging, navigation, exception boundaries, content deployment, and Designer behavior without duplicating host infrastructure.

## 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.

Start by researching the existing WinForms Blazor Hybrid composition and template structure; the issue does not name files, tests, or entry points. Map the WebView, lifetime, configuration, logging, navigation, exception, deployment, and Designer requirements before choosing an approach. Done includes appropriate tests and documentation, local and CI verification, and recorded design decisions, alternatives, dependencies, and follow-up work.

Written by the indexing model from the issue text.