Add Jest sample for Selenium load testing

[anushree-bstack]

Adds a jest/ folder mirroring the per-framework layout used by java/, junit-4/, junit-5/, and testng/. Tests use selenium-webdriver against the BrowserStack pod's hub at localhost:4444/wd/hub and target bstackdemo.com for add-to-cart and full checkout flows, parity with the WebdriverIO public sample.

• jest/browserstack-load.yml — Selenium + framework: jest, vus: 1, duration: 1m, us-east-1, references jest.config.js
• jest/package.json — jest + selenium-webdriver
• jest/jest.config.js — node env, runInBand-friendly
• jest/tests/add-to-cart.test.js — bstackdemo add-to-cart
• jest/tests/checkout.test.js — bstackdemo full checkout flow
• jest/README.md — 5-step setup (clone, npm install, CLI, run, dashboard)
• .gitignore — Node artifacts (node_modules, lockfiles)

[jhawarchirag]

Reviewed against the four existing samples (java/, junit-4/, junit-5/, testng/) to keep this consistent with what customers already see in the repo. Three changes needed before merge — all are parity gaps with the sibling samples, not new conventions:

1. Checkout test has no expect() and a different final-step flow than siblings — see inline comment on checkout.test.js.
2. Driver lifecycle is beforeAll/afterAll; siblings re-create per test.
3. Implicit wait + window().maximize() missing.

Non-blocking (pre-existing repo-wide, not introduced by this PR but worth a follow-up): brittle selectors (#\\33, react-select-2-option-0-0, deep float-cart chain), hardcoded sleep(500) after login, README OS↔arch swap in Linux binary links. These appear in every sample — best handled in a separate cleanup PR across all frameworks.

[anushree-bstack]

Updated (1cdab4a) — aligned both jest tests with the proven load-testing-backend/sample/jest-selenium scripts, which were validated end-to-end via UI + CLI on a real load-test run.

add-to-cart.test.js

• Wait for elements to be visible before reading their text — this is what fixes the empty cart-title (Expected "iPhone 12 Pro Max", Received "") that came up in local runs. The float-cart slides in with an animation, so the title node exists before its text is painted; reading too early returns "".
• Switched to the shorter descendant selector for the cart title and a beforeAll/afterAll session.

checkout.test.js

• Wait for the cart overlay to open before closing it.
• Routed the tail through Continue Shopping → Orders, matching the working sample.
• Wrapped interactions in located/visible/enabled waits.

Note: I haven't executed these locally (no Selenium hub on hand) — verified by matching the flow line-for-line against the known-working sample. Best to confirm with a CLI/pod run before merge.