Commit MWS backend source tree

The ASP.NET Core solution (mws.api/mws.application/mws.domain/
mws.infrastructure) existed only as untracked working files. Adding
it to version control, plus a .gitignore for build output and local
tooling directories, so the CQRS/mediator refactor plan has a real
git history to branch and diff against.

mws.infrastructure/Authentication/JwtTokenService.cs

@@ -0,0 +1,32 @@
+using System.IdentityModel.Tokens.Jwt;
+using System.Security.Claims;
+using System.Text;
+using Microsoft.IdentityModel.Tokens;
+using Mws.Application.Auth;
+
+namespace Mws.Infrastructure.Authentication;
+
+public class JwtTokenService(JwtOptions options) : ITokenService
+{
+    public string CreateToken(Guid userId, string username)
+    {
+        var claims = new List<Claim>
+        {
+            new(JwtRegisteredClaimNames.Sub, userId.ToString()),
+            new(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
+            new(ClaimTypes.Name, username),
+        };
+
+        var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(options.Secret));
+        var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);
+
+        var token = new JwtSecurityToken(
+            issuer: options.Issuer,
+            audience: options.Audience,
+            claims: claims,
+            expires: DateTime.UtcNow.Add(options.Expiration),
+            signingCredentials: creds);
+
+        return new JwtSecurityTokenHandler().WriteToken(token);
+    }
+}