Russian documentation enhancements

[zhoel-sherk]

• Filled empty handbook pages (dns, route, out)
• Enhanced DNS docs (hosts, types, config) with practical scenarios
• Enhanced config reference (general, experimental, ntp, tunnels, sub-rules, sniffer, tun) with tips
• Enhanced proxy/routing docs (common fields, TLS, VLESS, groups, providers, rules) — including typo fix in content.ru.md and duplicate section cleanup in rules/index.ru.md
• Added Keenetic integration tips (XKeen, nfqws2, sign-craze) to client docs
• Enhanced web panel guide with sign-craze/port conflict note
• Added missing Russian nav_translations for all proxy/listener protocols and other nav items
  Some files (sniff/index.ru.md, inbound/tun.ru.md, client/client.ru.md) include Keenetic-specific advice — happy to adjust on request.