test(api): Enhance async service layer mocking for resume upload route

[ThePriyanuj]

Closes #6806

Note: Replacing PR #8039 to provide a completely clean Git history after rebasing.

Implemented 5 mock integration tests for the resume upload route. This isolated test suite successfully bypasses the RateLimiter and parseResume functions using asynchronous service layer stubs.

Hi @Aamod007 — I rebased with the latest main to resolve the upstream CI pipeline failures and wiped all previous package-lock.json merge conflicts. This PR is now compressed into a single clean commit containing only the isolated route.mock-integrations.test.ts modifications. Ready for your review!

[retenta-bot]

This pull request enhances the testing framework by implementing mock integration tests for the resume upload route, which is a crucial part of our API. It builds on previous decisions to ensure that tests remain hermetic and deterministic, validating interactions with mocked dependencies without real network I/O. Thank you for your efforts in cleaning up the commit history and resolving CI issues. Looking forward to your review!

[github-actions]

📦 Next.js Bundle Size Report (Gzipped Sizes)

✨ No significant bundle size changes detected.

📊 Summary of Totals

Category	PR Size	Base Size	Difference
Total JS	3966.23 KB	3966.23 KB	0 B
Total CSS	330.26 KB	330.26 KB	0 B

[ThePriyanuj]

Hi @Aamod007! The new PR is up and the CI pipeline is 100% green. 🟢

I successfully implemented the Vitest mock class structure without triggering any ESLint any rules, and fixed the RateLimiter method signature updates. Could you please review and re-apply the level:intermediate and quality:clean labels from the old closed PR (#8039) when you have a moment? Thank you!