server: enable nullable annotations in legacy files

src/Yavsc.Server/Services/BlogSpotService.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using System.Diagnostics;
 using System.Security.Claims;
 using Microsoft.AspNetCore.Authorization;

src/Yavsc.Server/Services/ClaudeModerationService.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using Yavsc.Moderation;
 using Yavsc.Abstract.Interfaces;
 using Anthropic.SDK;

src/Yavsc.Server/Services/LiveProcessor.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using System.Collections.Concurrent;
 using System.Net.WebSockets;
 using Yavsc.Models;

src/Yavsc.Server/Services/MailSender.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using MailKit.Net.Smtp;
 using MailKit.Security;
 using Microsoft.Extensions.Logging;

src/Yavsc.Server/Services/PermissionHandler.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using System.Security.Claims;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Http;

src/Yavsc.Server/Services/ProfileService.cs

@@ -1,3 +1,5 @@
+#nullable enable annotations
+
 using System.Security.Claims;
 using IdentityModel;
 using IdentityServer8.Models;