Add sealed services

Also fix a missing IDisposable

Akari.Prototype.Server/Services/AkariPath.cs

@@ -8,7 +8,7 @@ using System.Threading.Tasks;
 
 namespace Akari.Prototype.Server.Services
 {
-    public class AkariPath
+    public sealed class AkariPath
     {
         private readonly AkariOptions _options;
 

Akari.Prototype.Server/Services/AuthLifetimeService.cs

@@ -8,7 +8,7 @@ using System.Threading.Tasks;
 
 namespace Akari.Prototype.Server.Services
 {
-    public class AuthLifetimeService : IHostedService
+    public sealed class AuthLifetimeService : IHostedService, IDisposable
     {
         public static TimeSpan CleanupInterval => TimeSpan.FromSeconds(5);
         public static TimeSpan AuthLifetime => TimeSpan.FromSeconds(30);

Akari.Prototype.Server/Services/FingerprintManager.cs

@@ -15,7 +15,7 @@ using System.Threading.Tasks;
 
 namespace Akari.Prototype.Server.Services
 {
-    public class FingerprintManager : IFingerprintManager
+    public sealed class FingerprintManager : IFingerprintManager
     {
         public const string FingerprintsPath = "fingerprints.json";
 

Akari.Prototype.Server/Services/MasterKeyService.cs

@@ -12,7 +12,7 @@ using Microsoft.Extensions.Logging;
 
 namespace Akari.Prototype.Server.Services
 {
-    public class MasterKeyService : IMasterKeyService, IDisposable
+    public sealed class MasterKeyService : IMasterKeyService, IDisposable
     {
         private record Config(string Hash, string KeySalt);