feat: switch gateway container to host network mode and replace host.docker.internal with 127.0.0.1

Change gateway service from bridge networking to host network mode to enable direct access to host network interfaces. Replace host.docker.internal references with 127.0.0.1 in gateway URLs and backend host configuration. Remove port mapping, extra_hosts, and explicit network attachments since host mode provides direct network access.

deploy/docker-compose.yml

@@ -71,6 +71,7 @@ services:
       dockerfile: gateway/Dockerfile
     depends_on:
       - backend
+    network_mode: host
     sysctls:
       net.ipv4.ip_forward: "1"
     cap_add:
@@ -78,17 +79,13 @@ services:
       - SYS_MODULE
     devices:
       - /dev/net/tun:/dev/net/tun
-    extra_hosts:
-      - "host.docker.internal:host-gateway"
-    ports:
-      - "${GATEWAY_UDP_PORT:-51900}:${GATEWAY_UDP_PORT:-51900}/udp"
     environment:
       GATEWAY_BOOTSTRAP_TOKEN: ${GATEWAY_BOOTSTRAP_TOKEN:-nexavpn-gateway-bootstrap}
       NEXAVPN_GATEWAY_ID: ${NEXAVPN_GATEWAY_ID:-}
       NEXAVPN_GATEWAY_NAME: ${NEXAVPN_GATEWAY_NAME:-primary-gateway}
       NEXAVPN_GATEWAY_LISTEN_PORT: ${GATEWAY_UDP_PORT:-51900}
-      NEXAVPN_GATEWAY_SYNC_URL: ${NEXAVPN_GATEWAY_SYNC_URL:-http://host.docker.internal:8080/api/v1/gateway-agent}
-      NEXAVPN_GATEWAY_BOOTSTRAP_URL: ${NEXAVPN_GATEWAY_BOOTSTRAP_URL:-http://host.docker.internal:8080/api/v1/gateway-agent/bootstrap}
+      NEXAVPN_GATEWAY_SYNC_URL: ${NEXAVPN_GATEWAY_SYNC_URL:-http://127.0.0.1:8080/api/v1/gateway-agent}
+      NEXAVPN_GATEWAY_BOOTSTRAP_URL: ${NEXAVPN_GATEWAY_BOOTSTRAP_URL:-http://127.0.0.1:8080/api/v1/gateway-agent/bootstrap}
       DEFAULT_GATEWAY_ENDPOINT: ${DEFAULT_GATEWAY_ENDPOINT:-localhost:${GATEWAY_UDP_PORT:-51900}}
       DEFAULT_VPN_CIDR: ${DEFAULT_VPN_CIDR:-100.96.0.0/24}
       NEXAVPN_API_TOKEN: ${NEXAVPN_API_TOKEN:-}
@@ -96,13 +93,10 @@ services:
       NEXAVPN_GATEWAY_INTERFACE: ${NEXAVPN_GATEWAY_INTERFACE:-wg0}
       NEXAVPN_UPLINK_INTERFACE: ${NEXAVPN_UPLINK_INTERFACE:-eth0}
       NEXAVPN_ENABLE_MASQUERADE: ${NEXAVPN_ENABLE_MASQUERADE:-true}
-      NEXAVPN_BACKEND_HOST: ${NEXAVPN_BACKEND_HOST:-host.docker.internal}
+      NEXAVPN_BACKEND_HOST: ${NEXAVPN_BACKEND_HOST:-127.0.0.1}
     volumes:
       - ./scripts/gateway-entrypoint.sh:/scripts/gateway-entrypoint.sh:ro
       - gateway-state:/var/lib/nexavpn
-    networks:
-      - gateway
-      - control
 
 volumes:
   postgres-data:
@@ -110,4 +104,3 @@ volumes:
 
 networks:
   control:
-  gateway: