fix(fxa-settings): prevent CJK button labels breaking one character per line

[vpomerleau]

Because

• Fork PRs don't build here, so CircleCI never reports on fix(fxa-settings): prevent CJK button labels breaking one character per line #20724.

This pull request

• Mirrors fix(fxa-settings): prevent CJK button labels breaking one character per line #20724 by @sreecharan-desu onto a branch in this repo so the suite runs.
• Commits are theirs, rebased onto main. No content changes.

Issue that this pull request solves

Mirror of #20724 — see that PR for the issue reference.

Checklist

Put an x in the boxes that apply

• My commit is GPG signed.
• If applicable, I have modified or added tests which pass locally.
• I have added necessary documentation (if appropriate).
• I have verified that my changes render correctly in RTL (if appropriate).
• I have manually reviewed all AI generated code.

[vpomerleau]

Marked as draft, there are some issues with button layout and latin languages with long text strings.

[sreecharan-desu]

pushed a follow-up on #20724 for the latin layout — swapped whitespace-nowrap for break-keep (word-break: keep-all).

checked the modal max-w-64 pair and a squeezed unit-row with the real l10n strings (en/de/nl/ja/ko). didn't run the full settings app, just the same flex markup against those strings.

squeezed unit-row (the original cjk stacking). left is no keep-all, right is keep-all:

modal pair in max-w-64. nowrap is what makes the long latin confirms unbreakable — de Zugangsschlüssel löschen and nl Wachtwoordsleutel verwijderen stay one line and get very wide. keep-all still stops ja/ko from stacking per character; en can sit on one row; de/nl still wrap as a pair because those compounds are long, they just aren't locked to one giant line: