Added CandidateDiag struct to RaceResult with per-candidate:
- address attempted
- result (ok / skipped:ipv6 / error:reason)
- elapsed time in ms
Surfaced in call-debug events:
- connect:dual_path_race_start now includes dial_order + peer_mapped
- connect:dual_path_race_done now includes candidate_diags array
Upgraded dual_path tracing from debug to info for IPv6 skips and
dial failures so they appear in logcat/console.
Helps diagnose why P2P fails on specific networks (5G CGNAT,
address-restricted NATs, etc).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>