Stable v2.6.38

• feat(import): map Plesk customers to existing panel customers (no more duplicates)
• chore(lint): fix misspell (cancelled → canceled) in import comment
• fix(import): thread source SSH port to data-copy + detach from request ctx
• fix(settings): persist user language — wrong context key silently dropped it
• fix(i18n): explicit language choice wins over account default on login