chore: vendor selva_core from jnwnlee/selva@d7d40a9

Pure PyTorch SelVA source for SelvaModelLoader/FeatureExtractor/Sampler nodes.
Imports rewritten from selva.* to selva_core.*. mel_converter.py: replaced
librosa.filters.mel with pure-numpy implementation to avoid librosa→numba→NumPy
version incompatibility in some ComfyUI environments.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

selva_core/utils/misc.py

@@ -0,0 +1,41 @@
+import importlib
+from typing import Optional
+
+from omegaconf import DictConfig, OmegaConf
+
+
+
+def instantiate_from_config(target: str, params: Optional[dict] = None):
+    """
+    Instantiate an object from a dotted path `target` and keyword `params`.
+    Common name: instantiate_from_config
+    """
+    if not target or not isinstance(target, str):
+        raise ValueError(f"Invalid target: {target!r}")
+    params = {} if params is None else params
+
+    # Convert OmegaConf DictConfig to plain dict if needed
+    try:
+        if isinstance(params, DictConfig):
+            params = OmegaConf.to_container(params, resolve=True)
+    except Exception:
+        pass
+
+    try:
+        module_path, attr_name = target.rsplit('.', 1)
+    except ValueError as e:
+        raise ValueError(f"Target must be like 'pkg.mod.Class', got {target!r}") from e
+
+    try:
+        module = importlib.import_module(module_path)
+    except ModuleNotFoundError as e:
+        raise ModuleNotFoundError(f"Could not import module '{module_path}' for target '{target}'.") from e
+
+    try:
+        obj = getattr(module, attr_name)
+    except AttributeError as e:
+        raise AttributeError(f"Module '{module_path}' has no attribute '{attr_name}' (from '{target}').") from e
+
+    if not callable(obj):
+        raise TypeError(f"Resolved target '{target}' is not callable.")
+    return obj(**dict(params))