feat: global instance in the builder's format, deglobalize, library content rules

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

src/Integrations/Divi/BlockTree/Block.php

@@ -141,6 +141,30 @@ final class Block extends Container
         return clone $this;
     }
 
+    /**
+     * A deep copy of this block under another name and attributes: opener and closer are
+     * regenerated, children and the text between them are kept, the void flag too. Opaque exactly
+     * when the Parser would make it so. GlobalInstance uses it to turn a library root into an
+     * instance and back.
+     *
+     * @param array<string, mixed> $attrs
+     */
+    public function copyAs(string $name, array $attrs): self
+    {
+        if (preg_match(self::NAME_PATTERN, $name) !== 1) {
+            throw new InvalidArgumentException(sprintf('"%s" is not a valid block name.', $name));
+        }
+
+        $copy = clone $this;
+        $copy->name = $name;
+        $copy->attrs = self::deepCloneAttrs($attrs);
+        $copy->rawOpen = null;
+        $copy->rawClose = null;
+        $copy->opaque = $name === 'divi/global-layout' || array_key_exists('globalModule', $attrs);
+
+        return $copy;
+    }
+
     public function __clone()
     {
         foreach ($this->parts as $position => $part) {