ResourceHelper.cs

using System.IO;
using System.Reflection;

namespace UCNLSalinity
{
    internal static class ResourceHelper
    {
        public static Stream GetResourceStream(string resourceName)
        {
            var assembly = Assembly.GetExecutingAssembly();
            var fullResourceName = $"UCNLSalinity.{resourceName}";

            var stream = assembly.GetManifestResourceStream(fullResourceName);
            if (stream == null)
            {
                var names = assembly.GetManifestResourceNames();
                throw new FileNotFoundException(
                    $"Resource '{fullResourceName}' not found. Available: {string.Join(", ", names)}");
            }

            return stream;
        }

        public static string GetResourceAsString(string resourceName)
        {
            using (var stream = GetResourceStream(resourceName))
            using (var reader = new StreamReader(stream))
            {
                return reader.ReadToEnd();
            }
        }
    }
}