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/imageCompare.ts

@@ -1,3 +1,4 @@
+import type { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
 import type { NodeOutputWith } from '@/schemas/apiSchema'
 import { api } from '@/scripts/api'
 import { app } from '@/scripts/app'
@@ -11,7 +12,7 @@ type ImageCompareOutput = NodeOutputWith<{
 useExtensionService().registerExtension({
   name: 'Comfy.ImageCompare',
 
-  async nodeCreated(node) {
+  async nodeCreated(node: LGraphNode) {
     if (node.constructor.comfyClass !== 'ImageCompare') return
 
     const [oldWidth, oldHeight] = node.size