[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/errors.py

@@ -0,0 +1,89 @@
+from __future__ import annotations
+
+
+class ErrorRaiseNode:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {"required": {}}
+
+    RETURN_TYPES = ("IMAGE",)
+    FUNCTION = "raise_error"
+    CATEGORY = "DevTools"
+    DESCRIPTION = "Raise an error for development purposes"
+
+    def raise_error(self):
+        raise Exception("Error node was called!")
+
+
+class ErrorRaiseNodeWithMessage:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {"required": {"message": ("STRING", {"multiline": True})}}
+
+    RETURN_TYPES = ()
+    OUTPUT_NODE = True
+
+    FUNCTION = "raise_error"
+    CATEGORY = "DevTools"
+    DESCRIPTION = "Raise an error with message for development purposes"
+
+    def raise_error(self, message: str):
+        raise Exception(message)
+
+
+class ExperimentalNode:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {"required": {}}
+
+    RETURN_TYPES = ()
+    OUTPUT_NODE = True
+    FUNCTION = "experimental_function"
+    CATEGORY = "DevTools"
+    DESCRIPTION = "A experimental node"
+
+    EXPERIMENTAL = True
+
+    def experimental_function(self):
+        print("Experimental node was called!")
+
+
+class DeprecatedNode:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {"required": {}}
+
+    RETURN_TYPES = ()
+    OUTPUT_NODE = True
+    FUNCTION = "deprecated_function"
+    CATEGORY = "DevTools"
+    DESCRIPTION = "A deprecated node"
+
+    DEPRECATED = True
+
+    def deprecated_function(self):
+        print("Deprecated node was called!")
+
+
+NODE_CLASS_MAPPINGS = {
+    "DevToolsErrorRaiseNode": ErrorRaiseNode,
+    "DevToolsErrorRaiseNodeWithMessage": ErrorRaiseNodeWithMessage,
+    "DevToolsExperimentalNode": ExperimentalNode,
+    "DevToolsDeprecatedNode": DeprecatedNode,
+}
+
+NODE_DISPLAY_NAME_MAPPINGS = {
+    "DevToolsErrorRaiseNode": "Raise Error",
+    "DevToolsErrorRaiseNodeWithMessage": "Raise Error with Message",
+    "DevToolsExperimentalNode": "Experimental Node",
+    "DevToolsDeprecatedNode": "Deprecated Node",
+}
+
+__all__ = [
+    "ErrorRaiseNode",
+    "ErrorRaiseNodeWithMessage",
+    "ExperimentalNode",
+    "DeprecatedNode",
+    "NODE_CLASS_MAPPINGS",
+    "NODE_DISPLAY_NAME_MAPPINGS",
+]