feat: Jellyfin plugin skeleton

- Plugin.cs: BasePlugin<PluginConfiguration>, Name 'Lessons'
- PluginConfiguration.cs: empty config class
- ServiceRegistrator.cs: IPluginServiceRegistrator for DI

Closes #2

plugin/Configuration/PluginConfiguration.cs

@@ -0,0 +1,7 @@
+using MediaBrowser.Model.Plugins;
+
+namespace Jellyfin.Plugin.Lessons.Configuration;
+
+public class PluginConfiguration : BasePluginConfiguration
+{
+}

plugin/Plugin.cs

@@ -0,0 +1,21 @@
+using MediaBrowser.Common.Plugins;
+using MediaBrowser.Model.Plugins;
+using MediaBrowser.Model.Serialization;
+using Microsoft.Extensions.Logging;
+using Jellyfin.Plugin.Lessons.Configuration;
+
+namespace Jellyfin.Plugin.Lessons;
+
+public class Plugin : BasePlugin<PluginConfiguration>
+{
+    public Plugin(IApplicationPaths appPaths, IXmlSerializer xmlSerializer)
+        : base(appPaths, xmlSerializer)
+    {
+    }
+
+    public override string Name => "Lessons";
+
+    public override Guid Id => Guid.Parse("a1b2c3d4-e5f6-7890-abcd-ef1234567890");
+
+    public override string Description => "Homeschool lesson plans with embedded media";
+}

plugin/ServiceRegistrator.cs

@@ -0,0 +1,11 @@
+using MediaBrowser.Common.Plugins;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Jellyfin.Plugin.Lessons;
+
+public class ServiceRegistrator : IPluginServiceRegistrator
+{
+    public void RegisterServices(IServiceCollection services)
+    {
+    }
+}