Improve cross-domain tracking and add "Always" script category

Move linker config into gtag('config') call with accept_incoming and
decorate_forms for reliable cross-domain linking. Capture _gl parameter
in sessionStorage to preserve attribution across navigation. Add
referrer-based attribution replay fallback so GA4 reports source/medium
instead of (not set) when UTMs are absent. Add "Always" script category
that executes without waiting for consent.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

includes/class-frontend.php

@@ -115,7 +115,6 @@ wait_for_update:c.wait_for_update||500
 });
 window.attCCHasConsent=false;
 }
-if(c.linker_domains&&c.linker_domains.length){g('set','linker',{'domains':c.linker_domains});}
 if(!sessionStorage.getItem('att_cc_attr')){
 var p=new URLSearchParams(window.location.search);
 var a={
@@ -128,9 +127,10 @@ ut:p.get('utm_term')||'',
 uo:p.get('utm_content')||'',
 gc:p.get('gclid')||'',
 dc:p.get('dclid')||'',
+gl:p.get('_gl')||'',
 t:Date.now()
 };
-if(a.r||a.us||a.gc){
+if(a.r||a.us||a.gc||a.gl){
 sessionStorage.setItem('att_cc_attr',JSON.stringify(a));
 }
 }
@@ -176,7 +176,7 @@ j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
 		if ( 'gtag' === $s['tracking_mode'] && ! empty( $s['ga4_measurement_id'] ) ) {
 			$id = esc_attr( $s['ga4_measurement_id'] );
 			return "<script async src=\"https://www.googletagmanager.com/gtag/js?id={$id}\"></script>
-<script>window.attCCGtag('config','{$id}');</script>";
+<script>(function(){var o={};var c=window.attCCConfig||{};if(c.linker_domains&&c.linker_domains.length){o.linker={domains:c.linker_domains,accept_incoming:true,decorate_forms:true};}window.attCCGtag('config','{$id}',o);})();</script>";
 		}
 
 		return '';