Better playwright tests

[flakey5]

Enter your suggestions in details:

Tests should include tests of actual content re #8248 and https://openjs-foundation.slack.com/archives/CVAMEJ4UV/p1761008932326439?thread_ts=1761008123.880979&cid=CVAMEJ4UV

[avivkeller]

FWIW E2E currently covers:

• That translations are working
• That the theme is interchangeable
• That search functionality works

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Even so, I don't think E2E would have caught this, since a PR didn't introduce a regression, rather, data we didn't expect did. Tests will all sorts of malformed and unexpected data may help, though.

[bmuenzenmeyer]

Yeah the only way to detect would have been timed testing of the site on some cron, like every couple minutes. Not impossible, but a lot of work. I suspect there are tools and services that could do this.

At the time this issue was suggested, we didn't yet know the root cause (data and timing)