Fix e2e (Playwright) output dir handling

[sentience]

This fixes two issues in the E2E (Playwright) build path when using npm (e.g. when using chromaui/action@latest in GitHub Actions with playwright: true):

• forward --output-dir correctly to build-archive-storybook
• recover correctly when Storybook writes the output directory in the newer (Storybook 10) multiline format

Problem

For E2E (Playwright) builds, Chromatic currently constructs the npm command to build a Storybook archive from Playwright test results like this:

npm exec build-archive-storybook --output-dir=/tmp/chromatic-...

With npm, that does not reliably pass --output-dir to the binary, so the build output ends up in ./storybook-static instead of the expected temp dir.

chromatic-cli already has a fallback for that case, where it detects the correct output directory by finding it in the Storybook CLI build log, but the parser only recognizes an older one-line log format (which seems to have been the format produced by Storybook 8). @chromatic-com/playwright@0.13.* has recently upgraded to Storybook 10, which outputs the build directory in a different, multi-line format, which chromatic-cli's fallback fails to parse. As a result, chromatic-cli cannot find the Storybook build output, and fails to find/validate the built test suite output with a message like this:

Error: Invalid test suite build at /tmp/chromatic--2600-OhzfouEzYsTN (check the build log)

Here's a sample build failure on one of my own projects triggered by the upgrade to @chromatic-com/playwright@0.13.x.

Fix

This PR fixes both issues:

• change npm E2E command construction to use npm exec -- ...
• make output directory parsing handle both:
  • Output directory: /path
  • Output directory: followed by the path on the next line

Why

This showed up for me when upgrading @chromatic-com/playwright, which moved the embedded Storybook version forward. The underlying npm forwarding issue was already there, but the newer Storybook log format stopped the existing recovery path from working. I originally reported it as chromaui/chromatic-e2e#312, mistaking it for a @chromatic-com/playwright issue, but on further investigation I traced the root cause to these issues in chromatic-cli – they were only triggered by the Storybook 10 upgrade in @chromatic-com/playwright.