refactor: improve TypeScript patterns in test files (Group 1/8) (#8253)

## Summary
Improves type safety in test files by replacing unsafe type patterns
with proper TypeScript idioms.

## Changes
- Define typed `TestWindow` interface extending `Window` for Playwright
tests with custom properties
- Use `Partial<HTMLElement>` with single type assertion for DOM element
mocks
- Remove redundant type imports
- Fix `console.log` → `console.warn` in test fixture

## Files Changed
16 test files across browser_tests, packages, and src/components

## Test Plan
- ✅ `pnpm typecheck` passes
- ✅ No new `any` types introduced
- ✅ All pre-commit hooks pass

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8253-refactor-improve-TypeScript-patterns-in-test-files-Group-1-8-2f16d73d365081548f9ece7bcf0525ee)
by [Unito](https://www.unito.io)

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

browser_tests/tests/vueNodes/interactions/links/linkInteraction.spec.ts

@@ -419,7 +419,7 @@ test.describe('Vue Node Link Interaction', () => {
     // This avoids relying on an exact path hit-test position.
     await comfyPage.page.evaluate(
       ([targetNodeId, targetSlot, clientPoint]) => {
-        const app = (window as any)['app']
+        const app = window['app']
         const graph = app?.canvas?.graph ?? app?.graph
         if (!graph) throw new Error('Graph not available')
         const node = graph.getNodeById(targetNodeId)
@@ -505,7 +505,7 @@ test.describe('Vue Node Link Interaction', () => {
     // This avoids relying on an exact path hit-test position.
     await comfyPage.page.evaluate(
       ([targetNodeId, targetSlot, clientPoint]) => {
-        const app = (window as any)['app']
+        const app = window['app']
         const graph = app?.canvas?.graph ?? app?.graph
         if (!graph) throw new Error('Graph not available')
         const node = graph.getNodeById(targetNodeId)