feat: make Swagger/Scalar available outside Development via UseSwagger flag

Previously Swagger UI was only registered in Development. Add a
'UseSwagger' config key so staging/production environments can opt in
without code changes.

EnvelopeGenerator.Server/EnvelopeGenerator.Server/Program.cs

@@ -383,9 +383,6 @@ try
     if (app.Environment.IsDevelopment())
     {
         app.UseWebAssemblyDebugging();
-        app.UseSwagger();
-        app.UseSwaggerUI();
-        app.MapScalarApiReference();
     }
     else
     {
@@ -393,6 +390,14 @@ try
         app.UseHsts();
     }
 
+    var useSwagger = app.Environment.IsDevelopment() || config.GetValue<bool>("UseSwagger");
+    if (useSwagger)
+    {
+        app.UseSwagger();
+        app.UseSwaggerUI();
+        app.MapScalarApiReference();
+    }
+
     // Set CORS policy
     app.UseCors("AllowSpecificOriginsPolicy");