fix: language filter also checks the title's original language (v1.0.0.15)

AllowedLanguages only filtered on each video's iso_639_1 tag, and TMDB
often tags subtitled foreign trailers as "en". With en,fr selected, 6 of
27 downloaded trailers were Korean, Chinese or Zulu titles. Candidates
now also need an allowed original_language (from the list results, so
no extra API calls).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Jellyfin.Plugin.CinemaTrailers4Jellyfins/Configuration/config.html

@@ -45,7 +45,9 @@
                     <fieldset class="verticalSection verticalSection-extrabottompadding">
                         <legend><h3 class="sectionTitle">Trailer Languages</h3></legend>
                         <p class="fieldDescription">
-                            Only download trailers in the selected languages.
+                            Only download trailers in the selected languages. Both the trailer and the
+                            movie/show itself (its original language) must be in one of them, so a
+                            subtitled foreign trailer is skipped.
                             Leave everything unchecked to allow all languages.
                         </p>
                         <div style="display:grid;grid-template-columns:1fr 1fr;gap:0 2em;">