fix(settings): wrap the scan-QR help link inside the phone frame

[dschom]

Because

• On the new pairing scan-QR page, long translations of the "Get help scanning" link (French, for one) overflow the phone graphic frame.

This pull request

• Caps the help link's width so long strings wrap onto a second line inside the phone screen.

Issue that this pull request solves

Closes: FXA-14486

Checklist

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• 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.

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Other information (Optional)

• The overlay does not grow the card, so a translation needing a third line would still clip below the artwork. The French string fits in two.

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