fix: anchor Divi name/id patterns at string end, number-advanced stays unknown, doc wording

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

src/Integrations/Divi/BlockTree/Serializer.php

@@ -9,7 +9,7 @@ namespace LIT\MCP\Integrations\Divi\BlockTree;
  * delimiters; changed or new blocks get delimiters generated exactly like WordPress'
  * get_comment_delimited_block_content() / serialize_block_attributes() do, which also
  * yields the escaping Divi expects inside $variable(…)$ payloads: json_encode()'s own
- * \" (an escaped quote inside a JSON string) is replaced by ", see ESCAPES below.
+ * \" (an escaped quote inside a JSON string) is replaced by \u0022, see ESCAPES below.
  */
 final class Serializer
 {