refactor: DiviSaver docblocks, one diviWritable field, REASON_CREATE with the constants (M-4, M-5, M-13)

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

src/Integrations/Divi/DiviIntegration.php

@@ -57,7 +57,7 @@ final class DiviIntegration implements Integration
      * @param (Closure(): bool)|null $libraryVisible Tools-tab gate for library entries at all (group
      *        "Divi-Bibliothek" not disabled, ruling P9); null = always.
      * @param (Closure(): bool)|null $diviWritable Whether lit/divi-insert is enabled – lit/divi-node-copy
-     *        follows it (ruling P9, E9); null = always.
+     *        and lit-library-insert follow it (ruling P9, E9, audit M2); null = always.
      * @param (Closure(): bool)|null $libraryInsertable Whether lit/library-insert is enabled –
      *        lit/divi-node-copy follows it for library entries as source (audit L5); null = always.
      */
@@ -128,10 +128,10 @@ final class DiviIntegration implements Integration
     }
 
     /**
-     * The group "Divi-Bibliothek" (lit/library-*), sharing this integration's library access;
-     * $diviWritable is whether lit/divi-insert is enabled (lit-library-insert follows it, audit M2).
+     * The group "Divi-Bibliothek" (lit/library-*), sharing this integration's library access and its
+     * $diviWritable gate (lit-library-insert follows lit/divi-insert, audit M2).
      */
-    public function library(?Closure $diviWritable = null): LibraryIntegration
+    public function library(): LibraryIntegration
     {
         $loader = $this->loader();
 
@@ -143,7 +143,7 @@ final class DiviIntegration implements Integration
             new DiviSaver(),
             $this->log,
             $this->modules,
-            $diviWritable
+            $this->diviWritable
         );
     }