fix: add explicit type annotations to extension callback parameters (#8966)

Fixes #8882

Adds explicit type annotations to all extension callback parameters
(`nodeCreated`, `beforeRegisterNodeDef`, `addCustomNodeDefs`) across 14
core extension files. While the types were already inferred from the
`ComfyExtension` interface, explicit annotations improve readability and
make the code self-documenting.

## Changes

- Annotate `node` parameter as `LGraphNode` in all `nodeCreated`
callbacks
- Annotate `nodeType` as `typeof LGraphNode` and `nodeData` as
`ComfyNodeDef` in all `beforeRegisterNodeDef` callbacks
- Annotate `defs` as `Record<string, ComfyNodeDef>` in
`addCustomNodeDefs`
- Add necessary type imports where missing

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8966-fix-add-explicit-type-annotations-to-extension-callback-parameters-30b6d73d36508125b074f509aa38145f)
by [Unito](https://www.unito.io)

src/extensions/core/customWidgets.ts

@@ -4,6 +4,7 @@ import { useChainCallback } from '@/composables/functional/useChainCallback'
 import type { CanvasPointerEvent } from '@/lib/litegraph/src/types/events'
 import { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
 import { LLink } from '@/lib/litegraph/src/litegraph'
+import type { ComfyNodeDef } from '@/schemas/nodeDefSchema'
 import { app } from '@/scripts/app'
 
 function applyToGraph(this: LGraphNode, extraLinks: LLink[] = []) {
@@ -190,7 +191,7 @@ function onCustomFloatCreated(this: LGraphNode) {
 
 app.registerExtension({
   name: 'Comfy.CustomWidgets',
-  beforeRegisterNodeDef(nodeType, nodeData) {
+  beforeRegisterNodeDef(nodeType: typeof LGraphNode, nodeData: ComfyNodeDef) {
     if (nodeData?.name === 'CustomCombo')
       nodeType.prototype.onNodeCreated = useChainCallback(
         nodeType.prototype.onNodeCreated,