Refactor EmailAccountDto and improve encryption logic

Refactored `EmailAccountDto` to focus on SMTP-related properties, removing unused fields. Updated `DependencyInjection` to configure data protection with a new key storage path. Simplified `DataProtectionEncryptionService` by removing redundant checks and error handling for encryption and decryption methods.

src/DigitalData.EmailProfiler.Infrastructure/DependencyInjection.cs

@@ -2,6 +2,7 @@ using DigitalData.EmailProfiler.Application.Common.Interfaces;
 using DigitalData.EmailProfiler.Infrastructure.Messaging;
 using DigitalData.EmailProfiler.Infrastructure.Queue;
 using DigitalData.EmailProfiler.Infrastructure.Services;
+using Microsoft.AspNetCore.DataProtection;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -43,9 +44,9 @@ public static class DependencyInjection
         services.AddHostedService<RabbitMqCommandConsumer>();
 
         // --- Data Protection (for encryption) ---
-        services.AddDataProtection();
-            // .PersistKeysToFileSystem(new DirectoryInfo(@"C:\ProgramData\EmailProfiler\Keys"))
-            // .SetApplicationName("EmailProfiler");
+        services.AddDataProtection()
+            .PersistKeysToFileSystem(new DirectoryInfo(@"C:\ProgramData\EmailService\Keys"))
+            .SetApplicationName("EmailProfiler");
 
         return services;
     }