Fix bug where stale cache causes media player to mix up episode names

Jellyfin.Plugin.Jellypod/Services/IPodcastStorageService.cs

@@ -10,6 +10,12 @@ namespace Jellyfin.Plugin.Jellypod.Services;
 /// </summary>
 public interface IPodcastStorageService
 {
+    /// <summary>
+    /// Gets the cached last modification time (synchronous, for cache key generation).
+    /// Returns default if database hasn't been loaded yet.
+    /// </summary>
+    DateTime LastModified { get; }
+
     /// <summary>
     /// Gets all subscribed podcasts.
     /// </summary>
@@ -57,4 +63,10 @@ public interface IPodcastStorageService
     /// </summary>
     /// <returns>The base path for podcast storage.</returns>
     string GetStoragePath();
+
+    /// <summary>
+    /// Gets the last time the database was modified.
+    /// </summary>
+    /// <returns>The last modification time, or null if unknown.</returns>
+    Task<DateTime?> GetLastModifiedAsync();
 }