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/saveImageExtraOutput.ts

@@ -1,3 +1,5 @@
+import type { LGraphNode } from '@/lib/litegraph/src/LGraphNode'
+import type { ComfyNodeDef } from '@/schemas/nodeDefSchema'
 import { applyTextReplacements } from '@/utils/searchAndReplace'
 
 import { app } from '../../scripts/app'
@@ -21,7 +23,10 @@ const saveNodeTypes = new Set([
 
 app.registerExtension({
   name: 'Comfy.SaveImageExtraOutput',
-  async beforeRegisterNodeDef(nodeType, nodeData) {
+  async beforeRegisterNodeDef(
+    nodeType: typeof LGraphNode,
+    nodeData: ComfyNodeDef
+  ) {
     if (saveNodeTypes.has(nodeData.name)) {
       const onNodeCreated = nodeType.prototype.onNodeCreated
       // When the SaveImage node is created we want to override the serialization of the output name widget to run our S&R