Part of #145.
`8c9bf0d` localized the settings views themselves; these eight files sit
in the same zone but were not in that pass: the subscription modal, the
child-user creation and password-change modals, both payment result
views, developer settings, and the backup/restore and account-deletion
modals.
Extends the `settings` namespace you established, following its key
naming — 59 keys added to `en/settings.json`. `src/i18n/config.js` is
untouched.
English only — no translations, no behaviour change. Every t() value is
checked against this branch's base: the string must appear
character-for-character in the code it replaces (71 call sites).
One deliberate structural detail: in `BackupRestoreModal` the warning
reads `<strong>Warning:</strong> Restoring a backup will…`. The label and
the sentence are separate keys and the `<strong>` stays in the JSX, so the
emphasis survives and no markup ends up in the dictionary.
If you'd rather keep developer settings hardcoded, say so and I'll drop
that file — it is the one screen here an end user never sees.
