fix(qa): run the macOS-only gates on Windows and Linux (#1061)

Seven QA scripts hard-coded macOS Google Chrome. They now share chromeExecutablePath(): PUPPETEER_EXECUTABLE_PATH when set, then macOS Chrome when installed, otherwise Puppeteer's managed browser. The cables screenshot path is built with fileURLToPath so it works on Windows. qa-overlay-baseline keeps its fixed Chrome because its baselines record the executable.

Co-authored-by: Sameh Khamis <[email protected]>

scripts/qa-chrome.mjs

@@ -0,0 +1,20 @@
+/**
+ * The browser for gates that drive an installed Chrome. These gates were
+ * written against macOS Google Chrome, which Windows and Linux do not have.
+ */
+import { existsSync } from 'node:fs';
+
+export const MACOS_CHROME =
+  '/Applications/Google Chrome.app/Contents/MacOS/Google Chrome';
+
+/**
+ * PUPPETEER_EXECUTABLE_PATH when set, then macOS Google Chrome when it is
+ * installed. Otherwise undefined, so Puppeteer launches the browser it manages.
+ */
+export function chromeExecutablePath({
+  env = process.env,
+  exists = existsSync,
+} = {}) {
+  if (env.PUPPETEER_EXECUTABLE_PATH) return env.PUPPETEER_EXECUTABLE_PATH;
+  return exists(MACOS_CHROME) ? MACOS_CHROME : undefined;
+}