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>

hosts/van.conf

@@ -0,0 +1,30 @@
+# hosts/van.conf — FriendlyElec NanoPi R5C, hostname "van" (Armbian).
+# /etc/vanlink.conf -> this file. See hosts/vanlink.conf.example for the variable list.
+
+WIFI_5G_IFACE=wlp1s0            # MediaTek MT7925E (PCIe); also carries the 2.4GHz AP
+WIFI_2G_IFACE=wlx3c3332002066
+LAN_IFACE=enP1p17s0
+STARLINK_IFACE=enP2p33s0
+WIFI_WAN_IFACE=wlan0            # not present on this host (kept for the failover config)
+ONBOARD_LAN_IFACE=
+
+GATEWAY_IP="10.42.1.1"
+GATEWAY_PREFIX="24"
+GATEWAY_NETWORK="10.42.1.0/24"
+DHCP_RANGE_START="10.42.1.10"
+DHCP_RANGE_END="10.42.1.254"
+DNS_RESOLVERS="1.1.1.1 8.8.8.8"
+
+MODEM_USB_VENDOR=2c7c
+NVME_DEVICE=
+NVME_FS_DEVICE=
+
+USB_BACKUP_ROOT_PART=
+USB_BACKUP_MOUNT=
+SD_BACKUP_UUID=39118305-4927-47a4-acc7-ba022f37af22
+
+ENABLE_COCKPIT=0
+ENABLE_LI3=1
+ENABLE_NVME_WATCH=0             # no NVMe on this board
+ENABLE_HA=1
+ENABLE_FRIGATE=1