feat: relay ping with RTT, server TOFU, lock icons (Phase 2 backport)
Rust JNI:
- nativePingRelay: QUIC connect with 3s timeout, returns RTT + server
certificate fingerprint as JSON. Static method, no engine needed.
Kotlin:
- WzpEngine.pingRelay() static wrapper
- SettingsRepository: TOFU fingerprint persistence (tofu_{address} keys)
- CallViewModel: pingAllServers() coroutine, lockStatus() helper,
PingResult/LockStatus data types
- InCallScreen: server chips show lock icon + RTT color (green/yellow),
"Ping All" button
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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