fix(captcha): close human-verification loop end-to-end

Rewrite captcha core around aksrt_captcha_config only, require captcha
on login/comment/SMS/phone auth and related gates, wire frontend token
collection, and remove dead dual-source security settings plus slider enqueue.

inc/classes/scripts-traits/trait-aksrt-scripts-part-1b.php

@@ -886,18 +886,6 @@ trait AKSRT_Scripts_Part_1b {
             );
         }
 
-        // Slider CAPTCHA (canvas-based puzzle verification)
-        $slider_captcha_js = get_template_directory() . '/assets/js/slider-captcha.js';
-        if (file_exists($slider_captcha_js)) {
-            wp_enqueue_script(
-                'aksrt-slider-captcha',
-                $base_uri . '/assets/js/slider-captcha.js',
-                [],
-                (string) filemtime($slider_captcha_js),
-                true
-            );
-        }
-
         // Instant page prefetch (hover to preload)
         $instant_page_js = get_template_directory() . '/assets/js/instant-page.js';
         if (file_exists($instant_page_js)) {