fix: full-form internal links follow the {{link:}} target rules (ruling P10)

One PostIdParser for {{link:}} and select_post; post_link_url_<type> needs a
living, readable, non-attachment target of exactly that type.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/Integrations/Divi/Pages/DiviDynamicSourcesAbility.php

@@ -205,12 +205,12 @@ final class DiviDynamicSourcesAbility implements Ability
             return '{{post:' . $post . '}}';
         }
 
-        if (! str_starts_with($name, 'post_link_url_')) {
+        if (! str_starts_with($name, DynamicContentRules::LINK_PREFIX)) {
             return null;
         }
 
-        // Review M-9: {{link:}} refuses attachments (status inherit); internal types ("_…") are no link targets.
-        $type = substr($name, strlen('post_link_url_'));
+        // Review M-9/P10: {{link:}} and the full form refuse attachments; internal types ("_…") are no link targets.
+        $type = substr($name, strlen(DynamicContentRules::LINK_PREFIX));
 
         return $type === 'attachment' || str_starts_with($type, '_') ? null : '{{link:<ID>}}';
     }