model : add HunyuanOCR support (#21395)

* HunyuanOCR: add support for text and vision models

- Add HunyuanOCR vision projector (perceiver-based) with Conv2d merge
- Add separate HUNYUAN_OCR chat template (content-before-role format)
- Handle HunyuanOCR's invalid pad_token_id=-1 in converter
- Fix EOS/EOT token IDs from generation_config.json
- Support xdrope RoPE scaling type
- Add tensor mappings for perceiver projector (mm.before_rms, mm.after_rms, etc.)
- Register HunYuanVLForConditionalGeneration for both text and mmproj conversion

* fix proper mapping

* Update gguf-py/gguf/tensor_mapping.py

Co-authored-by: Xuan-Son Nguyen <thichthat@gmail.com>

* Update tools/mtmd/clip.cpp

Co-authored-by: Xuan-Son Nguyen <thichthat@gmail.com>

* address comments

* update

* Fix typecheck

* Update convert_hf_to_gguf.py

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* Update convert_hf_to_gguf.py

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* Update convert_hf_to_gguf.py

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* Update convert_hf_to_gguf.py

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

---------

Co-authored-by: Xuan-Son Nguyen <thichthat@gmail.com>
Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

tools/mtmd/mtmd.cpp

@@ -406,6 +406,13 @@ struct mtmd_context {
                     img_end = "\n"; // prevent empty batch on llama-server
                     image_preproc = std::make_unique<mtmd_image_preprocessor_deepseekocr>(ctx_v);
                 } break;
+            case PROJECTOR_TYPE_HUNYUANOCR:
+                {
+                    // note: these use fullwidth ｜ (U+FF5C) and ▁ (U+2581) to match the tokenizer vocabulary
+                    img_beg = "<｜hy_place▁holder▁no▁100｜>";
+                    img_end = "<｜hy_place▁holder▁no▁101｜>";
+                    image_preproc = std::make_unique<mtmd_image_preprocessor_dyn_size>(ctx_v);
+                } break;
             default:
                 throw std::runtime_error(string_format("%s: unexpected vision projector type %d\n", __func__, proj));
         }