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/WebSocketConnection.cs

@@ -22,6 +22,15 @@ namespace Emby.Server.Implementations.HttpServer
 
     /// <summary>
     /// Class WebSocketConnection.
+    /// Represents an authenticated WebSocket connection to a Jellyfin client.
+    ///
+    /// Authentication is performed during connection establishment in WebSocketManager.
+    /// The client must provide a valid API token via one of these methods:
+    /// - Query parameter: ws://server:8096/socket?api_key=TOKEN
+    /// - Authorization header: MediaBrowser Token="..."
+    /// - Legacy headers: X-Emby-Token or X-MediaBrowser-Token
+    ///
+    /// Once established, AuthorizationInfo contains the authenticated user/device information.
     /// </summary>
     public class WebSocketConnection : IWebSocketConnection
     {
@@ -47,7 +56,7 @@ namespace Emby.Server.Implementations.HttpServer
         /// </summary>
         /// <param name="logger">The logger.</param>
         /// <param name="socket">The socket.</param>
-        /// <param name="authorizationInfo">The authorization information.</param>
+        /// <param name="authorizationInfo">The authorization information containing authenticated user/device details.</param>
         /// <param name="remoteEndPoint">The remote end point.</param>
         public WebSocketConnection(
             ILogger<WebSocketConnection> logger,

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;