ci: fix browser-test workflow by setting PUPPETEER_EXECUTABLE_PATH

[mroderick]

Problem

The browser-test job started failing with:

Error: Could not find Chrome (ver. 147.0.7727.57). This can occur if either
 1. you did not perform an installation before running the script (e.g. `npx puppeteer browsers install chrome`) or
 2. your cache path is incorrectly configured (which is: /home/runner/.cache/puppeteer).

Failed run

Cause

Puppeteer v24 (installed via puppeteer@^24.42.0) no longer falls back to the system-installed google-chrome-stable when the cached browser is missing. The workflow sets PUPPETEER_SKIP_CHROMIUM_DOWNLOAD: 1, so nothing is downloaded during npm ci, and Puppeteer exits immediately.

Fix

Set PUPPETEER_EXECUTABLE_PATH to the system Chrome binary so Puppeteer uses it instead of looking in its cache. This env var is read by Puppeteer's getConfiguration() and is picked up by both @mochify/driver-puppeteer (used in test-coverage) and direct puppeteer.launch() calls (used in test-headless / test-webworker).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.40%. Comparing base (49bf019) to head (8faa5c1).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2721   +/-   ##
=======================================
  Coverage   97.40%   97.40%           
=======================================
  Files          39       39           
  Lines        1810     1810           
=======================================
  Hits         1763     1763           
  Misses         47       47           

Flag	Coverage Δ
unit	97.40% <ø> (ø)

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