fix(vpn): fix DNS iptables rules and add NET_RAW cap

DNS OUTPUT was restricted to -o wg0, but routing decision happens
after iptables OUTPUT — so DNS to VPN-internal addresses (198.18.0.x)
was blocked before the kernel selected the outgoing interface.
Allow DNS unconditionally; routing still sends it through wg0.

Add NET_RAW capability so ping works inside the container.

Docker/podman-compose.yml

@@ -7,6 +7,7 @@ services:
     cap_add:
       - NET_ADMIN
       - SYS_MODULE
+      - NET_RAW
     sysctls:
       - net.ipv4.ip_forward=1
       - net.ipv4.conf.all.src_valid_mark=1