deploy: host config from /etc/vanlink.conf (hosts/<hostname>.conf)

deploy.conf is replaced by one versioned file per host plus an example.
deploy.sh validates the config, renders every template with a generic
token loop, refuses to install output with leftover @TOKENs and gains
--check/--templates. LAN_USB_IFACE is renamed LAN_IFACE.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

ap/22-van-lan.network

@@ -2,7 +2,7 @@
 # gets DHCP/DNS from the same dnsmasq as Wi-Fi clients. NM must leave this device
 # alone (see van-ap-unmanaged.conf) for networkd to own it here.
 [Match]
-Name=@LAN_USB_IFACE@
+Name=@LAN_IFACE@
 
 [Link]
 RequiredForOnline=no

ap/van-ap-unmanaged.conf

@@ -2,4 +2,4 @@
 # The AP wlans (5GHz + 2.4GHz) and the wired LAN ports (USB dongle + onboard
 # eth0) are all owned by systemd-networkd/hostapd (bridged into br0), so
 # NetworkManager must not touch them.
-unmanaged-devices=interface-name:@WIFI_5G_IFACE@;interface-name:@WIFI_2G_IFACE@;interface-name:@LAN_USB_IFACE@;interface-name:eth0
+unmanaged-devices=interface-name:@WIFI_5G_IFACE@;interface-name:@WIFI_2G_IFACE@;interface-name:@LAN_IFACE@;interface-name:eth0