Create VB-to-shared-model and C# feature samples with migration guidance

[KlausLoeffelmann]

Objective

Create paired VB and C# samples plus an incremental migration example from ApplicationEvents.vb/MyApplication to the shared model. Show how existing VB projects remain valid, how applications opt in feature-by-feature, and where behavior intentionally differs.

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.