[NeiL978]

Add Traditional Chinese (Taiwan) translation

Adds a zh-TW locale with 601 translated messages covering the existing translatable pages, dialogs, banners, and status messages. Registers the locale and its date/time formats so it can be selected from the language menu.

Uses terminology common in Taiwan and preserves interpolation variables, linked messages, and plural forms.

Validation:

• Matched translation keys, interpolation variables, linked messages, and plural forms against English.
• Compiled and rendered all 601 messages with vue-i18n in zh-TW.
• pnpm typecheck passed.
• git diff --check passed.
• The contributor tested the development build and confirmed that the translation looked correct.

[CLAassistant]

All committers have signed the CLA.