Remove GetClaimValue extension from EnvelopeAuthExtensions

The GetClaimValue method, which delegated to GetRequiredClaim for retrieving claim values by type, has been removed from the EnvelopeAuthExtensions class. Other functionality in the class remains unchanged.

EnvelopeGenerator.API/Extensions/EnvelopeAuthExtensions.cs

@@ -27,14 +27,6 @@ public static class EnvelopeAuthExtensions
         throw new InvalidOperationException(message);
     }
 
-    /// <summary>
-    /// Retrieves a claim value by type.
-    /// </summary>
-    /// <param name="user">The current claims principal.</param>
-    /// <param name="claimType">The claim type to resolve.</param>
-    /// <returns>The claim value.</returns>
-    public static string GetClaimValue(this ClaimsPrincipal user, string claimType) => user.GetRequiredClaim(claimType);
-
     /// <summary>
     /// Gets the authenticated envelope UUID from the claims.
     /// </summary>