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/HttpServer/WebSocketManager.cs

@@ -18,6 +18,25 @@ using Microsoft.Extensions.Logging;
 
 namespace Emby.Server.Implementations.HttpServer
 {
+    /// <summary>
+    /// Manages WebSocket connections with authentication support.
+    ///
+    /// Clients should authenticate when connecting to WebSocket endpoints by providing an API token
+    /// through one of these methods:
+    ///
+    /// 1. Query String Parameter (Recommended):
+    ///    - URL: ws://jellyfin-server:8096/socket?api_key=YOUR_API_TOKEN
+    ///    - JavaScript: const ws = new WebSocket(`ws://jellyfin-server:8096/socket?api_key=${token}`);
+    ///
+    /// 2. Query String Parameter (Legacy):
+    ///    - URL: ws://jellyfin-server:8096/socket?ApiKey=YOUR_API_TOKEN
+    ///
+    /// 3. Authorization Header:
+    ///    - Header: MediaBrowser Device="...", Token="YOUR_API_TOKEN"
+    ///
+    /// The API token can be obtained from the server's API key management interface or
+    /// generated for specific clients/devices.
+    /// </summary>
     public class WebSocketManager : IWebSocketManager
     {
         private readonly IWebSocketListener[] _webSocketListeners;