refactor to unify data fetching and define abstract API for re-use

Jellyfin.Plugin.SRFPlay/Services/Interfaces/IMediaCompositionFetcher.cs

@@ -0,0 +1,23 @@
+using System.Threading;
+using System.Threading.Tasks;
+using Jellyfin.Plugin.SRFPlay.Api.Models;
+
+namespace Jellyfin.Plugin.SRFPlay.Services.Interfaces;
+
+/// <summary>
+/// Interface for fetching media composition with caching support.
+/// </summary>
+public interface IMediaCompositionFetcher
+{
+    /// <summary>
+    /// Gets media composition by URN, using cache if available.
+    /// </summary>
+    /// <param name="urn">The URN to fetch.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <param name="cacheDurationOverride">Optional override for cache duration (e.g., 5 min for livestreams).</param>
+    /// <returns>The media composition, or null if not found.</returns>
+    Task<MediaComposition?> GetMediaCompositionAsync(
+        string urn,
+        CancellationToken cancellationToken,
+        int? cacheDurationOverride = null);
+}