fix: order validation checks by parameter position in stats/base/dists/cauchy/mode

Reorder NaN guards so checks follow declaration order `(x0, gamma)`.
Behavior unchanged: any matching branch returns `NaN`.

Author: claude

lib/node_modules/@stdlib/stats/base/dists/cauchy/mode/lib/main.js

@@ -46,8 +46,8 @@ var isnan = require( '@stdlib/math/base/assert/is-nan' );
 */
 function mode( x0, gamma ) {
 	if (
-		isnan( gamma ) ||
 		isnan( x0 ) ||
+		isnan( gamma ) ||
 		gamma <= 0.0
 	) {
 		return NaN;