Add MedMind recovery and Steam authentication

Services/EmailService.cs

@@ -0,0 +1,37 @@
+using System.Net;
+using System.Net.Mail;
+using System;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Configuration;
+
+namespace GameAuthApi.Services;
+
+public class EmailService
+{
+    private readonly IConfiguration _config;
+
+    public EmailService(IConfiguration config) => _config = config;
+
+    public virtual async Task SendPasswordResetCodeAsync(string recipient, string code)
+    {
+        var host = _config["Email:SmtpHost"];
+        var sender = _config["Email:Sender"];
+        if (string.IsNullOrWhiteSpace(host) || string.IsNullOrWhiteSpace(sender))
+            throw new InvalidOperationException("SMTP email delivery is not configured.");
+
+        using var message = new MailMessage(sender, recipient)
+        {
+            Subject = "Your MedMind password reset code",
+            Body = $"Your MedMind verification code is {code}. It expires in 15 minutes. If you did not request this, you can ignore this email.",
+            IsBodyHtml = false
+        };
+        using var client = new SmtpClient(host, int.TryParse(_config["Email:SmtpPort"], out var port) ? port : 587)
+        {
+            EnableSsl = !bool.TryParse(_config["Email:UseTls"], out var tls) || tls
+        };
+        var username = _config["Email:Username"];
+        if (!string.IsNullOrWhiteSpace(username))
+            client.Credentials = new NetworkCredential(username, _config["Email:Password"]);
+        await client.SendMailAsync(message);
+    }
+}