Chore: Actions updates and cleanup (#8377)

## Summary

...

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8377-WIP-Chore-Actions-updates-and-cleanup-2f66d73d3650818483a8dffa32a6f245)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Amp <amp@ampcode.com>

.github/workflows/ci-tests-unit.yaml

@@ -16,21 +16,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
-      - name: Install pnpm
-        uses: pnpm/action-setup@v4
-        with:
-          version: 10
-
-      - name: Use Node.js
-        uses: actions/setup-node@v4
-        with:
-          node-version: 'lts/*'
-          cache: 'pnpm'
-
-      - name: Install dependencies
-        run: pnpm install --frozen-lockfile
+      - name: Setup frontend
+        uses: ./.github/actions/setup-frontend
 
       - name: Run Vitest tests
         run: pnpm test:unit