Each video connection item (TMDB/TVDB) now has a Test button that behaves like
music's: saves the key, hits POST /api/video/enrichment/<svc>/test, and toasts
the result via the shared showToast — isolated (own endpoint, own data-attr
handler, reuses the .test-button CSS).
- Client .test() pings TMDB /configuration and TVDB /login to verify the key.
- Endpoint returns {success,message,error}; unknown service -> 404.
94 tests green; music untouched.