fix(i18n): resolve cross-namespace keys via root translator (../ never worked)

[shukiv]

Bug

Several components call t('../namespace.key') (or t('../../namespace.key')) to reach a key in a different top-level namespace. next-intl has no relative (../) namespace navigation — the string is treated as a literal key inside the current namespace, isn't found, and next-intl returns the raw fallback.

Most visible case: the bulk Not spam toolbar button in the junk folder shows a tooltip of literally email_list.../context_menu.not_spam instead of the translated label. The batch spam/undo-spam toasts and a few settings strings hit the same bug (less visible because they're transient or English-only fallbacks that happen to read fine).

Fix

Resolve cross-namespace keys through a root translator (useTranslations() with no namespace) and reference the key by its absolute path — no ../.

Affected call sites:

• components/email/email-list.tsx — context_menu.not_spam (button title) + 5 email_viewer.spam.* toasts
• components/settings/account-settings.tsx — 3× common.unknown
• components/settings/about-data-settings.tsx — settings.import_success / import_error / save_success

No string/key changes; every target key already exists at its absolute path.

Testing

• Junk folder → select messages → Not spam tooltip now shows the translated label (e.g. Hebrew "לא ספאם") instead of the raw key
• Batch mark-as-spam / not-spam toasts show real text
• Settings → Account "Unknown" placeholders and About → import/reset alerts localize correctly
• tsc clean; lint clean (no new warnings)