feat: add asterisk pjsip integration

- infrastructure/docker/asterisk.Dockerfile: Asterisk 22.10.1 LTS compilado
  do fonte oficial (Debian trixie nao distribui mais o pacote asterisk),
  com PJSIP, AMI, ARI, res_odbc/res_config_odbc, cdr_adaptive_odbc,
  cel_odbc, app_queue
- infrastructure/asterisk/config: templates renderizados no entrypoint
  (secrets via envsubst, nunca versionados) + sorcery.conf/extconfig.conf
  para PJSIP realtime, dialplan de teste (extensao 600)
- infrastructure/postgres/init/002-asterisk-realtime.sql: tabelas
  ps_endpoints/ps_auths/ps_aors/ps_contacts/ps_endpoint_id_ips/
  ps_registrations/cdr/cel no schema 'asterisk'
- infrastructure/nftables: protege AMI/ARI/SIP contra acesso pela LAN
  (interface ens18), trazido da Fase 9 do TODO para ja, sem afetar SSH
  nem a rede interna do Docker
- docker-compose.yml: servico asterisk em network_mode: host (RTP);
  Postgres publicado em 127.0.0.1:5432 (nao 0.0.0.0) para o Asterisk
  alcanca-lo, ja que host network nao enxerga a rede Docker interna

Testado: AMI login, ARI com auth (401 sem auth), pjsip realtime
consultando Postgres sem erro, dialplan originate -> CDR e CEL gravados
corretamente, healthcheck do compose passando.

infrastructure/nftables/b2bcall-nftables.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=B2BCall custom nftables rules (protects Asterisk admin ports)
+After=docker.service network-online.target
+Wants=network-online.target
+PartOf=docker.service
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStartPre=-/usr/sbin/nft delete table inet b2bcall_fw
+ExecStart=/usr/sbin/nft -f /opt/b2bcall/infrastructure/nftables/b2bcall.nft
+ExecStop=/usr/sbin/nft delete table inet b2bcall_fw
+
+[Install]
+WantedBy=multi-user.target