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/Chapters/ChapterManager.cs

@@ -227,7 +227,7 @@ public class ChapterManager : IChapterManager
 
         if (saveChapters && changesMade)
         {
-            SaveChapters(video, chapters);
+            await SaveChaptersAsync(video, chapters, cancellationToken).ConfigureAwait(false);
         }
 
         DeleteDeadImages(currentImages, chapters);
@@ -240,19 +240,56 @@ public class ChapterManager : IChapterManager
     {
         // Remove any chapters that are outside of the runtime of the video
         var validChapters = chapters.Where(c => c.StartPositionTicks < video.RunTimeTicks).ToList();
-        _chapterRepository.SaveChapters(video.Id, validChapters);
+        // Note: Using sync wrapper for backward compatibility
+        _chapterRepository.SaveChaptersAsync(video.Id, validChapters, CancellationToken.None)
+            .GetAwaiter()
+            .GetResult();
+    }
+
+    /// <inheritdoc />
+    public async Task SaveChaptersAsync(Video video, IReadOnlyList<ChapterInfo> chapters, CancellationToken cancellationToken = default)
+    {
+        // Remove any chapters that are outside of the runtime of the video
+        var validChapters = chapters.Where(c => c.StartPositionTicks < video.RunTimeTicks).ToList();
+        await _chapterRepository
+            .SaveChaptersAsync(video.Id, validChapters, cancellationToken)
+            .ConfigureAwait(false);
     }
 
     /// <inheritdoc />
     public ChapterInfo? GetChapter(Guid baseItemId, int index)
     {
-        return _chapterRepository.GetChapter(baseItemId, index);
+        // Note: Using sync wrapper for backward compatibility
+        return _chapterRepository
+            .GetChapterAsync(baseItemId, index, CancellationToken.None)
+            .GetAwaiter()
+            .GetResult();
+    }
+
+    /// <inheritdoc />
+    public async Task<ChapterInfo?> GetChapterAsync(Guid baseItemId, int index, CancellationToken cancellationToken = default)
+    {
+        return await _chapterRepository
+            .GetChapterAsync(baseItemId, index, cancellationToken)
+            .ConfigureAwait(false);
     }
 
     /// <inheritdoc />
     public IReadOnlyList<ChapterInfo> GetChapters(Guid baseItemId)
     {
-        return _chapterRepository.GetChapters(baseItemId);
+        // Note: Using sync wrapper for backward compatibility
+        return _chapterRepository
+            .GetChaptersAsync(baseItemId, CancellationToken.None)
+            .GetAwaiter()
+            .GetResult();
+    }
+
+    /// <inheritdoc />
+    public async Task<IReadOnlyList<ChapterInfo>> GetChaptersAsync(Guid baseItemId, CancellationToken cancellationToken = default)
+    {
+        return await _chapterRepository
+            .GetChaptersAsync(baseItemId, cancellationToken)
+            .ConfigureAwait(false);
     }
 
     /// <inheritdoc />