JustHold i18n

• Locales: zh-hant (default/primary) and en, defined in i18n/routing.ts with localePrefix: 'always' (e.g. /zh-hant/holdings, /en/holdings).
• Public app routes live under app/[locale]/…. UI copy lives in messages/zh-hant.json and messages/en.json — add keys there; don't hardcode user-facing strings in components when a message namespace already exists.
• Prefer Traditional Chinese first; ship en when a translation is ready.
• Admin exception: app/admin/ is English-only (no [locale] segment). Don't wrap admin screens in next-intl routing.
• Content/R2 locale keys must match routing: zh-hant and en (see lib/r2.ts and the justhold-mdx-content skill).