Added missing severity levels

Author: jschick04

src/EventLogExpert.Eventing.Tests/EventResolvers/EventResolverBaseTests.cs

@@ -1624,13 +1624,15 @@ public void ResolveEvent_WithSeverityLevel_ShouldResolveLevelString()
         // Arrange
         var resolver = new TestEventResolver();
 
+        // ETW level 0 is "LogAlways" but Windows Event Viewer renders it as "Information"
         var testCases = new[]
         {
             (Level: (byte)0, Expected: "Information"),
+            (Level: (byte)1, Expected: "Critical"),
             (Level: (byte)2, Expected: "Error"),
             (Level: (byte)3, Expected: "Warning"),
             (Level: (byte)4, Expected: "Information"),
-            (Level: (byte)5, Expected: "5")
+            (Level: (byte)5, Expected: "Verbose")
         };
 
         foreach (var testCase in testCases)

src/EventLogExpert.Eventing/Helpers/SeverityMethods.cs

@@ -3,21 +3,31 @@
 
 namespace EventLogExpert.Eventing.Helpers;
 
+/// <summary>Severity levels with values matching ETW standard levels (1–5).</summary>
 public enum SeverityLevel
 {
-    Information,
-    Warning,
-    Error
+    Critical = 1,
+    Error = 2,
+    Warning = 3,
+    Information = 4,
+    Verbose = 5
 }
 
 public static class Severity
 {
+    /// <summary>Maps an ETW level byte to its display string.</summary>
+    /// <remarks>
+    /// ETW level 0 is technically "LogAlways", but the Windows Event Viewer MMC and
+    /// wevtutil both render it as "Information". We match that behavior intentionally.
+    /// </remarks>
     public static string GetString(byte? level) => level switch
     {
-        0 => nameof(SeverityLevel.Information),
+        0 => nameof(SeverityLevel.Information), // LogAlways — rendered as Information by Windows
+        1 => nameof(SeverityLevel.Critical),
         2 => nameof(SeverityLevel.Error),
         3 => nameof(SeverityLevel.Warning),
         4 => nameof(SeverityLevel.Information),
+        5 => nameof(SeverityLevel.Verbose),
         _ => level?.ToString() ?? string.Empty
     };
 }