Fix race condition in magic link token verification and typo in auth error message

- Hold SELECT FOR UPDATE lock within transaction by using tx directly instead of separate WithConn, ensuring mutual exclusion when multiple requests race to verify the same token
- Fix "resouce" → "resource" typo in authentication error messages

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/server/gqlutils/directives/session/session.go

@@ -92,7 +92,7 @@ func Directive(ctx context.Context, obj any, next graphql.Resolver, required Ses
 		if identity == nil {
 			return nil, gqlutils.Unauthenticatedf(
 				ctx,
-				"authentication is required to access this resouce",
+				"authentication is required to access this resource",
 			)
 		}
 	case SessionRequirementNone: