fix(wpmc 1.1.0): review polish — continue on bad permalink, ACF guard, drop suppress_filters, process-isolated AJAX test

- Redirect::handle: continue instead of return when get_permalink fails on a row (allow trying next row)
- Helpers::acf_ready() now public so Redirect can guard get_field('page_unic', ...) consistently
- Drop suppress_filters=false from get_posts (was risky on sites with query-altering plugins)
- @runInSeparateProcess for DOING_AJAX test (replaces Z-prefix ordering hack)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

includes/class-helpers.php

@@ -11,7 +11,7 @@ final class Helpers
     private static array $page_unic_cache = [];
     private static int $bypass_depth = 0;
 
-    private static function acf_ready(): bool
+    public static function acf_ready(): bool
     {
         return \did_action('acf/init') > 0;
     }