Method flattenLayers

src/api/pdf.ts:2975–2977

* Flatten all Optional Content Groups (layers) in the document. * * This removes the OCProperties dictionary from the catalog, which: * - Makes ALL layer content unconditionally visible (nothing is deleted) * - Removes the layer panel/toggle UI from PDF viewers * - Content that was in

()

   * ```
   */
  flattenLayers(): FlattenLayersResult {
    return LayerUtils.flattenLayers(this.ctx);
  }

  // ─────────────────────────────────────────────────────────────────────────────
  // Annotation Flattening