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.

Emby.Server.Implementations/ScheduledTasks/Tasks/ChapterImagesTask.cs

@@ -137,7 +137,9 @@ public class ChapterImagesTask : IScheduledTask
 
             try
             {
-                var chapters = _chapterManager.GetChapters(video.Id);
+                var chapters = await _chapterManager
+                    .GetChaptersAsync(video.Id, cancellationToken)
+                    .ConfigureAwait(false);
 
                 var success = await _chapterManager.RefreshChapterImages(video, directoryService, chapters, extract, true, cancellationToken).ConfigureAwait(false);