chore(connd): connection report for troubleshooting

[vmenge]

adds dns resolution and connectivity diagnostics to the network change reporter, to help troubleshoot issues like being stuck on ConnectedSite when connectivity actually works.

new

• resolved::Resolved module wrapping systemd-resolved's org.freedesktop.resolve1 d-bus interface via zbus_systemd

  • resolve_hostname(iface, hostname) — resolves a hostname on a specific interface, returns addresses, canonical name, and response flags (cache/network/authenticated/etc)
  • link_status(iface) — per-link dns status: current dns server, all dns servers, search/routing domains, default route

• net_changed_reporter::report() added, reporting:

  • connection event state
  • active connections with gateway/dns info
  • per-interface resolvectl status and resolvectl query results
  • connectivity check http response details (ok/fail based on status code)

changed

• ActiveConn now includes ipv4_gateway, ipv4_dns, ipv6_gateway, ipv6_dns fields
• active_connections() uses ip_interface() instead of interface() to get the actual ip-bearing interface (fixes wwan showing as cdc-wdm0 instead of wwan0)