feat(metadata-overwrite): support wired SAMPLER input on sampler field

The sampler field now accepts either a manual string or a SAMPLER
connection. When wired, the sampler name is extracted from the
KSAMPLER object's sampler_function __name__ (sample_euler -> euler),
with special-casing for dpm_fast/dpm_adaptive local closures and
uni_pc/uni_pc_bh2 function names.

- sampler input declared as "STRING,SAMPLER" with widgetType STRING,
  mirroring the existing model field union pattern
- shared collect_overwrite_params() handles the non-str branch so the
  node and the metadata extractor conversion logic stay in sync;
  unrecognized sampler functions are logged and skipped
- note: ddim is constructed by ComfyUI as euler with random inpaint,
  so the ddim name is unrecoverable and extracts as euler

py/nodes/metadata_overwrite.py

@@ -71,10 +71,18 @@ class MetadataOverwriteLM:
                     },
                 ),
                 "sampler": (
-                    "STRING",
+                    "STRING,SAMPLER",
                     {
                         "default": "",
-                        "tooltip": "Sampler name. Only overwrites when non-empty.",
+                        "widgetType": "STRING",
+                        "tooltip": (
+                            "Sampler name. Fill in the name manually or "
+                            "connect a SAMPLER output (e.g. KSamplerSelect) "
+                            "— the sampler name is then extracted "
+                            "automatically. Note: ddim is recorded as "
+                            "euler (ComfyUI internal representation). "
+                            "Only overwrites when non-empty."
+                        ),
                     },
                 ),
                 "scheduler": (
@@ -164,6 +172,8 @@ class MetadataOverwriteLM:
         The ``model`` field accepts either a manual string or a wired MODEL
         (ModelPatcher) connection; in the latter case the underlying model
         name is extracted from the patcher's ``cached_patcher_init`` and
-        stored as a ComfyUI-style relative path.
+        stored as a ComfyUI-style relative path.  The ``sampler`` field
+        likewise accepts a manual string or a wired SAMPLER (KSAMPLER)
+        connection, from which the sampler name is extracted automatically.
         """
         return (collect_overwrite_params(kwargs),)