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

Emby.Server.Implementations/AppBase/BaseConfigurationManager.cs

@@ -10,6 +10,7 @@ namespace Emby.Server.Implementations.AppBase
     using System.Globalization;
     using System.IO;
     using System.Linq;
+    using System.Reflection;
     using System.Threading;
     using MediaBrowser.Common.Configuration;
     using MediaBrowser.Common.Events;
@@ -306,6 +307,32 @@ namespace Emby.Server.Implementations.AppBase
 
         private object LoadConfiguration(string path, Type configurationType)
         {
+            // Try JSON first, then fallback to XML for backward compatibility
+            var jsonPath = Path.ChangeExtension(path, ".json");
+
+            // Try loading from .json if it exists
+            if (File.Exists(jsonPath))
+            {
+                try
+                {
+                    var method = typeof(ConfigurationHelper).GetMethod(
+                        nameof(ConfigurationHelper.GetJsonConfiguration),
+                        System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.Public);
+
+                    if (method is not null)
+                    {
+                        var genericMethod = method.MakeGenericMethod(configurationType);
+                        return genericMethod.Invoke(null, new object[] { jsonPath })
+                            ?? throw new InvalidOperationException("JSON deserialization returned null.");
+                    }
+                }
+                catch (Exception ex)
+                {
+                    Logger.LogError(ex, "Error loading JSON configuration file: {Path}", jsonPath);
+                }
+            }
+
+            // Fall back to XML for backward compatibility
             try
             {
                 if (File.Exists(path))