[refactor] reorganize devtools test nodes into modules (#6020)

## Summary

Refactored monolithic devtools node definitions into organized module
structure for better maintainability and separation of concerns.

## Changes

- **What**: Split 700+ line `dev_nodes.py` into modular structure under
`tools/devtools/nodes/` with categorized files: `errors.py`,
`inputs.py`, `models.py`, `remote.py`
- **Dependencies**: None

## Review Focus

Module import structure and ensure all node registrations are properly
preserved in the consolidated mappings.

**Before:**
```
tools/devtools/
├── __init__.py
└── dev_nodes.py (738 lines)
```

**After:**
```
tools/devtools/
├── __init__.py
├── dev_nodes.py (65 lines - imports only)
└── nodes/
    ├── __init__.py (consolidated mappings)
    ├── errors.py (error/debug nodes)
    ├── inputs.py (input/widget nodes)
    ├── models.py (model/patch nodes)
    └── remote.py (remote/combo nodes)
```

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6020-refactor-reorganize-devtools-test-nodes-into-modules-2896d73d365081e89efef7e88ca8fee3)
by [Unito](https://www.unito.io)

tools/devtools/nodes/models.py

@@ -0,0 +1,84 @@
+from __future__ import annotations
+
+import os
+
+import torch
+
+import comfy.utils as utils
+from comfy.model_patcher import ModelPatcher
+import nodes
+import folder_paths
+
+
+class DummyPatch(torch.nn.Module):
+    def __init__(self, module: torch.nn.Module, dummy_float: float = 0.0):
+        super().__init__()
+        self.module = module
+        self.dummy_float = dummy_float
+
+    def forward(self, *args, **kwargs):
+        if isinstance(self.module, DummyPatch):
+            raise Exception(f"Calling nested dummy patch! {self.dummy_float}")
+
+        return self.module(*args, **kwargs)
+
+
+class ObjectPatchNode:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "model": ("MODEL",),
+                "target_module": ("STRING", {"multiline": True}),
+            },
+            "optional": {
+                "dummy_float": ("FLOAT", {"default": 0.0}),
+            },
+        }
+
+    RETURN_TYPES = ("MODEL",)
+    FUNCTION = "apply_patch"
+    CATEGORY = "DevTools"
+    DESCRIPTION = "A node that applies an object patch"
+
+    def apply_patch(
+        self, model: ModelPatcher, target_module: str, dummy_float: float = 0.0
+    ) -> ModelPatcher:
+        module = utils.get_attr(model.model, target_module)
+        work_model = model.clone()
+        work_model.add_object_patch(target_module, DummyPatch(module, dummy_float))
+        return (work_model,)
+
+
+class LoadAnimatedImageTest(nodes.LoadImage):
+    @classmethod
+    def INPUT_TYPES(s):
+        input_dir = folder_paths.get_input_directory()
+        files = [
+            f
+            for f in os.listdir(input_dir)
+            if os.path.isfile(os.path.join(input_dir, f)) and f.endswith(".webp")
+        ]
+        files = folder_paths.filter_files_content_types(files, ["image"])
+        return {
+            "required": {"image": (sorted(files), {"animated_image_upload": True})},
+        }
+
+
+NODE_CLASS_MAPPINGS = {
+    "DevToolsObjectPatchNode": ObjectPatchNode,
+    "DevToolsLoadAnimatedImageTest": LoadAnimatedImageTest,
+}
+
+NODE_DISPLAY_NAME_MAPPINGS = {
+    "DevToolsObjectPatchNode": "Object Patch Node",
+    "DevToolsLoadAnimatedImageTest": "Load Animated Image",
+}
+
+__all__ = [
+    "DummyPatch",
+    "ObjectPatchNode",
+    "LoadAnimatedImageTest",
+    "NODE_CLASS_MAPPINGS",
+    "NODE_DISPLAY_NAME_MAPPINGS",
+]