Implement configuration and strongly typed options integration

## Objective

Implement approved defaults and builder extensions for JSON, environment, command-line, user secrets where appropriate, environment-specific configuration, options binding, validation, and change notifications. Make startup failures actionable and avoid desktop-hostile web assumptions.

## 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.

The issue names no files, tests, or entry points, so begin by locating the WinForms startup and configuration/options integration areas. Review the existing defaults, builders, binding, validation, notifications, and environment-specific behavior, then add appropriate tests and documentation and verify locally and in CI.

Written by the indexing model from the issue text.