expandEntry cleared Name for external subscriptions and single links
with empty remark, so Clash/JSON fell back to the client email. Keep
each link's original name (#fragment / vmess ps); use the row remark
when set. Pass remark from the client form for single external links.
Fixes#6032
Add a Links tab to the client form for attaching third-party share
links and remote subscription URLs per client. They are merged into
the client's raw/JSON/Clash subscription output: links are emitted
verbatim and parsed for JSON/Clash; subscription URLs are fetched
(cached, with a short timeout) and their configs merged in.
i18n keys added across all 13 locales.