Thread a lang parameter through render_markdown and every section
helper so the same report dict can render an English or Russian
report; inline _t() calls carry the strings, findings fall back from
_ru fields to their English siblings. write_report now emits a third
.ru.md file alongside .json and .md, and render_markdown can stamp a
sibling cross-link line right after the H1.
unavailable() only ever read module.errors for the placeholder detail
text, so a deliberately skipped section (speed in --quick or target
mode, which reports its reason as a warning, not an error) always
fell through to the generic 'no data was collected for this section'
line even though the real reason ('speedtest skipped in target mode')
was sitting right there in the json. spec says a skipped speedtest
must say why, not just that it's missing.
target mode's filename fell back to the local machine's egress asn
unconditionally, so 'netcheck --target AS15169' wrote report_<local-asn>_*
instead of report_AS15169_*. meta.target already carries the right
subject when one was given; prefer it and fall back to the egress asn
only in auto mode.
