i18n(zh-TW): restore the {count} plural in statisticYesterday

[owgreen-dev]

statisticYesterday is an ICU plural in the source:

en     {count, plural, one{1 yesterday} other{{count} yesterday}}
zh     {count, plural, =1{昨天} other{{count}天前}}
zh-TW  昨天

Traditional Chinese collapsed it to the singular text, so the reading-statistics row reads 昨天 whatever count is — two days ago and ten days ago both render as "yesterday".

This restores the plural using the same form the simplified Chinese file already uses, so the two stay consistent:

zh-TW  {count, plural, =1{昨天} other{{count}天前}}

Nothing else in the file is touched. Caught with an open-source i18n checker; after the change npx @shipi18n/cli check lib/l10n -s en reports zh-TW clean.

Full scan for this repo: https://shipi18n.com/oss#anx-reader