feat(metadata-overwrite): support wired MODEL input on model field

The model field now accepts either a manual string or a MODEL connection.
When wired, the model name is extracted from the patcher's
cached_patcher_init (registered by core loaders load_checkpoint_guess_config
and load_diffusion_model, preserved through LoRA clones) and converted to a
ComfyUI-style relative name via config model roots.

- model input declared as "STRING,MODEL" with widgetType STRING, so the
  text widget and the dual-type connection slot coexist; non-STRING/MODEL
  links are rejected by frontend and backend type validation
- UNETLoaderLM GGUF branch now registers a custom cached_patcher_init reload
  factory so GGUF models participate in name extraction and ModelPatcher
  deepclone/dynamic machinery
- shared collect_overwrite_params() helper keeps the node and the metadata
  extractor conversion logic in sync; extraction failures are logged instead
  of silently dropping the overwrite

py/metadata_collector/node_extractors.py

@@ -2,7 +2,8 @@ import json
 import os
 import re
 
-from .constants import CLIP_SKIP_SENTINEL, MODELS, PROMPTS, SAMPLING, LORAS, SIZE, IMAGES, IS_SAMPLER, OVERWRITE, METADATA_OVERWRITE_FIELDS
+from .constants import MODELS, PROMPTS, SAMPLING, LORAS, SIZE, IMAGES, IS_SAMPLER, OVERWRITE
+from .overwrite_utils import collect_overwrite_params
 
 
 def _store_checkpoint_metadata(metadata, node_id, model_name):
@@ -1233,14 +1234,7 @@ class MetadataOverwriteExtractor(NodeMetadataExtractor):
         if not inputs:
             return
 
-        overwrite_params = {}
-        for key in METADATA_OVERWRITE_FIELDS:
-            value = inputs.get(key)
-            if key == "clip_skip":
-                if value != CLIP_SKIP_SENTINEL:
-                    overwrite_params[key] = value
-            elif value:  # truthy — only overwrite when user provided a real value
-                overwrite_params[key] = value
+        overwrite_params = collect_overwrite_params(inputs)
 
         if overwrite_params:
             metadata.setdefault(OVERWRITE, {})