feat: NostrVPN mesh + VPN card UI + nvpn v0.3.7

- VPN card: relay URLs, device management, invite QR, add participant
- Backend: vpn.invite, vpn.add-participant, vpn.peer-config RPCs
- nvpn v0.3.7 system service (fixes event processing bug in v0.3.4)
- First-boot: auto-configure nvpn with node identity and endpoint
- Service: AF_NETLINK for WireGuard, NoNewPrivileges=no for sudo wg
- TASK-50: networking stack reliability from first install

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

core/archipelago/src/api/rpc/dispatcher.rs

@@ -240,8 +240,11 @@ impl RpcHandler {
             "vpn.status" => self.handle_vpn_status().await,
             "vpn.configure" => self.handle_vpn_configure(params).await,
             "vpn.disconnect" => self.handle_vpn_disconnect().await,
+            "vpn.invite" => self.handle_vpn_invite().await,
+            "vpn.add-participant" => self.handle_vpn_add_participant(params).await,
             "vpn.create-peer" => self.handle_vpn_create_peer(params).await,
             "vpn.list-peers" => self.handle_vpn_list_peers().await,
+            "vpn.peer-config" => self.handle_vpn_peer_config(params).await,
             "vpn.remove-peer" => self.handle_vpn_remove_peer(params).await,
             "remote.setup" => self.handle_remote_setup(params).await,