v2.3.1 - Ideogram 4 structured-control recipe corrected

Fixed

• Ideogram 4 structured-control nodes restored (they are real). v2.3.0 wrongly claimed the
  Create Bounding Boxes -> Build JSON Prompt (Ideogram) flow had "no dedicated bounding-box or JSON-builder
  node." Those nodes exist in current ComfyUI core: CreateBoundingBoxes (comfy_extras/nodes_bounding_boxes.py;
  outputs preview / bboxes (BOUNDING_BOX) / elements (ARRAY)), BuildJsonPromptIdeogram ("Build JSON
  Prompt (Ideogram)", nodes_json_prompt.py; the ARRAY plus high_level_description / background / style /
  aesthetics / lighting / medium / color_palette COLORS -> a DICT caption), and Ideogram4Scheduler
  (nodes_ideogram4.py). The v2.3.0 note was written after checking only nodes_ideogram.py (V3 / V4 only)
  against a local core (0.25.1) that predated these modules, and no template uses them yet; the
  CreateBoundingBoxes widget landed in frontend v1.48.2 (2026-07-11). MODELS.md now documents the real
  buildable chain (CreateBoundingBoxes -> BuildJsonPromptIdeogram -> Ideogram 4), confirmed from the node
  source. The Grok 1K / 2K, ModelMergeKrea2 and quant_int8_convrot.py corrections from v2.3.0 stand.