Gluetun: pass full single-peer WireGuard config to the container

The compose only forwarded VPN_SERVICE_PROVIDER, VPN_TYPE and the private
key, so Gluetun could not form a tunnel. Forward the peer public key,
endpoint IP/port, addresses, allowed IPs and keepalive interval. Add
matching placeholders to .env.example (current Gluetun uses the
single-peer WIREGUARD_* model, not the old WIREGUARD_PEERS_* names).

dankclaw/compose.yaml

@@ -16,6 +16,12 @@ services:
       VPN_SERVICE_PROVIDER: "${VPN_SERVICE_PROVIDER}"
       VPN_TYPE: "${VPN_TYPE}"
       WIREGUARD_PRIVATE_KEY: "${WIREGUARD_PRIVATE_KEY}"
+      WIREGUARD_ADDRESSES: "${WIREGUARD_ADDRESSES}"
+      WIREGUARD_PUBLIC_KEY: "${WIREGUARD_PUBLIC_KEY}"
+      WIREGUARD_ENDPOINT_IP: "${WIREGUARD_ENDPOINT_IP}"
+      WIREGUARD_ENDPOINT_PORT: "${WIREGUARD_ENDPOINT_PORT}"
+      WIREGUARD_ALLOWED_IPS: "${WIREGUARD_ALLOWED_IPS}"
+      WIREGUARD_PERSISTENT_KEEPALIVE_INTERVAL: "${WIREGUARD_PERSISTENT_KEEPALIVE_INTERVAL}"
     ports:
       # SearXNG's published port lives on gluetun (network_mode: service:gluetun)
       - "8081:8080"