fix(a11y): inline placeholder title uses <p>, not <h4> (#482)

The inline placeholder for blocked third-party embeds (YouTube,
Vimeo, …) hard-wired a <h4> element for the service title. When the
placeholder is rendered inside arbitrary page content, this almost
always breaks the document outline (a <section> already running on
<h2>/<h3> suddenly contains a stray <h4> with no parent heading).
Lighthouse and other a11y audits flag this as a heading-order issue.

Switches the tag to <p> so it no longer participates in the heading
outline, but keeps the existing .consent-inline-title class plus the
Bootstrap-style .h4 utility class. Themes/styles that already target
the class or .h4 typography stay visually identical; no CSS change
needed (consent_inline.css selectors are class-based).

Themes that *do* want a real heading can still override the fragment
locally via theme/private/fragments/ConsentManager/inline_placeholder.php.

Author: danspringer

fragments/ConsentManager/inline_placeholder.php

@@ -79,7 +79,7 @@ class="consent-inline-thumbnail"
 }
 ?>
                     </div>
-                    <h4 class="consent-inline-title"><?= rex_escape($options['title'] ?? $service['service_name'] ?? $inline_title_fallback) ?></h4>
+                    <p class="consent-inline-title h4"><?= rex_escape($options['title'] ?? $service['service_name'] ?? $inline_title_fallback) ?></p>
                     <p class="consent-inline-notice"><?= rex_escape($options['privacy_notice'] ?? (isset($service['placeholder_text']) && '' !== $service['placeholder_text'] ? $service['placeholder_text'] : $inline_privacy_notice)) ?></p>
                     <p class="consent-inline-action-text"><?= rex_escape($inline_action_text) ?></p>