[codex] Fix activity video route parameter handling

[YoonKeumJae]

Summary

• Accept the lowercased Azure Functions route parameter for activity video detail and delete handlers.
• Add regression coverage for lowercased route params and optional activity video metadata preservation.

Root cause

Azure Functions exposes the route parameter as activityvideoid, while the controller only read activityVideoId. Detail, update, and delete calls could use an undefined id after create or delete from the Admin UI.

Validation

• npm test --prefix Elevate.Server