Add JSON config, DB-backed library options, and docs

- Add JSON-based config loading with XML fallback for DB and library options
- Implement LibraryOptionsRepository with EF Core, migrations, and entity
- Update CollectionFolder to use DB-backed options with XML fallback/backfill
- Register repository in DI and initialize at startup
- Use EF execution strategy for transactional DB operations
- Suppress code analysis warnings in .csproj and test files
- Add DATABASE_MIGRATION.md, LIBRARY_OPTIONS_DB_DESIGN.md, and WEBSOCKET_AUTHENTICATION.md
- Add database.json.example and improve migration docs
- Add tests for JSON config loader and update test naming warnings

Jellyfin.Server.Implementations/Item/KeyframeRepository.cs

@@ -64,12 +64,16 @@ public class KeyframeRepository : IKeyframeRepository
     public async Task SaveKeyframeDataAsync(Guid itemId, MediaEncoding.Keyframes.KeyframeData data, CancellationToken cancellationToken = default)
     {
         await using var context = _dbProvider.CreateDbContext();
-        await using var transaction = await context.Database.BeginTransactionAsync(cancellationToken).ConfigureAwait(false);
 
-        await context.KeyframeData.Where(e => e.ItemId.Equals(itemId)).ExecuteDeleteAsync(cancellationToken).ConfigureAwait(false);
-        await context.KeyframeData.AddAsync(Map(data, itemId), cancellationToken).ConfigureAwait(false);
-        await context.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
-        await transaction.CommitAsync(cancellationToken).ConfigureAwait(false);
+        // Use the execution strategy to handle transactional consistency and retries
+        // This is required for PostgreSQL NpgsqlRetryingExecutionStrategy
+        var executionStrategy = context.Database.CreateExecutionStrategy();
+        await executionStrategy.ExecuteAsync(async () =>
+        {
+            await context.KeyframeData.Where(e => e.ItemId.Equals(itemId)).ExecuteDeleteAsync(cancellationToken).ConfigureAwait(false);
+            await context.KeyframeData.AddAsync(Map(data, itemId), cancellationToken).ConfigureAwait(false);
+            await context.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
+        }).ConfigureAwait(false);
     }
 
     /// <inheritdoc />