feat: StoredNodeGuard keeps S7/S26 for nodes moving between posts (E6)

Refuses, for users without unfiltered_html, non-Divi blocks, raw text parts,
unreadable opaque blocks, code modules, builder-only paths (also below the
state value), strings that are not sanitizer-stable and stored $variable
references that VariableRef::canonical() refuses or would change (P2, P3).

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

src/Integrations/Divi/Compose/ValueCleaner.php

@@ -93,7 +93,17 @@ final class ValueCleaner
      */
     public function kindOf(string $module, string $path, ?string $subKey = null): ValueKind
     {
-        return $this->kind($module, $path, $subKey, $subKey);
+        return $this->kindAt($module, $path, $subKey, $subKey);
+    }
+
+    /**
+     * The kind clean() routes a string to that sits below the state value of $path: $subName is
+     * the first key there, $key the nearest key above the string (step 5, like cleanNode()).
+     * StoredNodeGuard checks stored values against exactly this routing.
+     */
+    public function kindAt(string $module, string $path, ?string $subName, ?string $key): ValueKind
+    {
+        return $this->kind($module, $path, $subName, $key);
     }
 
     /**