feat: add genre, rating, and avoid-repeats trailer filters

Trailer selection now supports three optional filters:
- Genre match: prefer trailers whose fake-movie genre overlaps with the
  feature being played (requires TMDB genres in NFO)
- Age rating ceiling: exclude trailers rated higher than the feature
  (requires TMDB certification in NFO)
- Avoid repeats: cycle through all trailers before replaying any;
  resets per-user once the pool is exhausted

Genre and certification are fetched from TMDB at download time via a
single /movie/{id}?append_to_response=release_dates call and written
into the fake-movie NFO as <genre> and <mpaa> tags. All filters fall
back to the full unfiltered pool when no match is found.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Jellyfin.Plugin.CinemaTrailers4Jellyfins/Services/TmdbService.cs

@@ -19,6 +19,8 @@ namespace Jellyfin.Plugin.CinemaTrailers4Jellyfins.Services
         public int? Year => DateTime.TryParse(ReleaseDate, out var d) ? d.Year : (int?)null;
     }
 
+    public record TmdbMovieMetadata(IReadOnlyList<string> Genres, string? Certification);
+
     public class TmdbService : IDisposable
     {
         private readonly HttpClient _httpClient;
@@ -187,6 +189,77 @@ namespace Jellyfin.Plugin.CinemaTrailers4Jellyfins.Services
             return null;
         }
 
+        /// <summary>
+        /// Returns the genre names and US theatrical certification (G, PG, PG-13, R, NC-17)
+        /// for a movie. Uses a single /movie/{id}?append_to_response=release_dates call.
+        /// </summary>
+        public async Task<TmdbMovieMetadata> GetMovieMetadataAsync(
+            string tmdbId,
+            string apiKey,
+            CancellationToken ct)
+        {
+            try
+            {
+                var url = $"{BaseUrl}/movie/{tmdbId}?append_to_response=release_dates&language=en-US";
+                using var request = new HttpRequestMessage(HttpMethod.Get, url);
+                ApplyAuth(request, apiKey);
+                using var response = await _httpClient.SendAsync(request, ct).ConfigureAwait(false);
+                response.EnsureSuccessStatusCode();
+                var json = await response.Content.ReadAsStringAsync(ct).ConfigureAwait(false);
+                using var doc = JsonDocument.Parse(json);
+
+                var genres = new List<string>();
+                if (doc.RootElement.TryGetProperty("genres", out var genreArr))
+                {
+                    foreach (var g in genreArr.EnumerateArray())
+                    {
+                        if (g.TryGetProperty("name", out var name))
+                        {
+                            var genreName = name.GetString();
+                            if (!string.IsNullOrEmpty(genreName))
+                                genres.Add(genreName);
+                        }
+                    }
+                }
+
+                string? certification = null;
+                if (doc.RootElement.TryGetProperty("release_dates", out var releaseDates)
+                    && releaseDates.TryGetProperty("results", out var rdResults))
+                {
+                    foreach (var country in rdResults.EnumerateArray())
+                    {
+                        if (!country.TryGetProperty("iso_3166_1", out var iso)
+                            || !string.Equals(iso.GetString(), "US", StringComparison.OrdinalIgnoreCase))
+                            continue;
+
+                        if (!country.TryGetProperty("release_dates", out var dates))
+                            break;
+
+                        foreach (var date in dates.EnumerateArray())
+                        {
+                            if (!date.TryGetProperty("certification", out var cert))
+                                continue;
+                            var certStr = cert.GetString();
+                            if (!string.IsNullOrWhiteSpace(certStr))
+                            {
+                                certification = certStr;
+                                break;
+                            }
+                        }
+                        break;
+                    }
+                }
+
+                return new TmdbMovieMetadata(genres.AsReadOnly(), certification);
+            }
+            catch (OperationCanceledException) { throw; }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "|CinemaTrailers4Jellyfins| GetMovieMetadata failed for TMDB ID {Id}", tmdbId);
+                return new TmdbMovieMetadata(Array.Empty<string>(), null);
+            }
+        }
+
         public async Task<List<TmdbVideo>> GetTrailersAsync(
             string tmdbId,
             string apiKey,