Refactor PostgreSQL provider: multi-schema & async prep

- Refactor migrations and provider to use multiple PostgreSQL schemas, each matching a legacy SQLite database (activitylog, authentication, displaypreferences, library, users).
- All tables, foreign keys, and indexes are now schema-qualified; Down migration drops tables by schema.
- Provider ensures schemas exist before migrations; entities are mapped to correct schemas in OnModelCreating.
- Add support for max-pool-size, min-pool-size, and multiplexing connection options; update logging accordingly.
- VACUUM ANALYZE now runs per schema during scheduled optimization.
- TruncateAllTablesAsync now truncates tables with schema qualification.
- README updated with schema structure, new options, and multiplexing warnings.
- CacheDecorator now calls async repository methods using .GetAwaiter().GetResult(), with documentation.
- Lays groundwork for full async/await and multiplexing support in the database layer.

MediaBrowser.Controller/Library/IMediaSourceManager.cs

@@ -42,6 +42,22 @@ namespace MediaBrowser.Controller.Library
         /// <returns>IEnumerable&lt;MediaStream&gt;.</returns>
         IReadOnlyList<MediaStream> GetMediaStreams(MediaStreamQuery query);
 
+        /// <summary>
+        /// Gets the media streams asynchronously.
+        /// </summary>
+        /// <param name="itemId">The item identifier.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>IReadOnlyList&lt;MediaStream&gt;.</returns>
+        Task<IReadOnlyList<MediaStream>> GetMediaStreamsAsync(Guid itemId, CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// Gets the media streams asynchronously.
+        /// </summary>
+        /// <param name="query">The query.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>IReadOnlyList&lt;MediaStream&gt;.</returns>
+        Task<IReadOnlyList<MediaStream>> GetMediaStreamsAsync(MediaStreamQuery query, CancellationToken cancellationToken = default);
+
         /// <summary>
         /// Gets the media attachments.
         /// </summary>
@@ -56,6 +72,22 @@ namespace MediaBrowser.Controller.Library
         /// <returns>IEnumerable&lt;MediaAttachment&gt;.</returns>
         IReadOnlyList<MediaAttachment> GetMediaAttachments(MediaAttachmentQuery query);
 
+        /// <summary>
+        /// Gets the media attachments asynchronously.
+        /// </summary>
+        /// <param name="itemId">The item identifier.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>IReadOnlyList&lt;MediaAttachment&gt;.</returns>
+        Task<IReadOnlyList<MediaAttachment>> GetMediaAttachmentsAsync(Guid itemId, CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// Gets the media attachments asynchronously.
+        /// </summary>
+        /// <param name="query">The query.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>IReadOnlyList&lt;MediaAttachment&gt;.</returns>
+        Task<IReadOnlyList<MediaAttachment>> GetMediaAttachmentsAsync(MediaAttachmentQuery query, CancellationToken cancellationToken = default);
+
         /// <summary>
         /// Gets the playback media sources.
         /// </summary>