feat(netinfra): migrate DHCP from pfv-netboot to netinfra-01/02 with failover

ISC DHCP server with failover-peer (primary/secondary) deployed on
pfv-netinfra-01 (192.168.3.252) and pfv-netinfra-02 (192.168.3.253). Both
servers in "normal" state, load-balancing 333 active leases.

Migration details:
- Copied all 37 host reservations + subnet/pool config from pfv-netboot
- DHCP lease database copied from netboot for zero-disruption cutover
- DNS servers changed from 192.168.3.250 (netboot) to 252/253 (netinfra pair)
- NTP servers (252/253) added to DHCP options (netboot didn't hand out NTP)
- Netmask on both nodes fixed /24 -> /22 to match the network
- Webmin + DHCP module installed on both nodes (port 10000, SSL)
- pfv-netboot DHCP stopped + disabled
- Tested via sectestbed-sandbox (DHCP lease obtained from 252, verified DNS/NTP/gateway)
- Snapshot "pre-dhcp-migration" on sandbox as rollback point

Configs: netinfra/dhcp/dhcpd-{primary,secondary}.conf
Plan + results: netinfra/dhcp-migration.md

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

docs/docmap.md

@@ -3,7 +3,7 @@
 > **Index of all documentation in this repo.** Agents must update this file
 > whenever a doc is added, removed, or substantively changed.
 
-> **Last updated:** 2026-07-29
+> **Last updated:** 2026-07-29 (DHCP migration)
 
 ## Kubernetes Architecture ([`k8s/`](k8s/))
 
@@ -44,6 +44,7 @@ Server provisioning, security hardening, DNS/NTP configuration.
 
 | Document | Description | Last Reviewed |
 |----------|-------------|---------------|
+| [`../netinfra/dhcp-migration.md`](../netinfra/dhcp-migration.md) | DHCP migration: pfv-netboot → netinfra-01/02 (ISC failover-peer, COMPLETE) | 2026-07-29 |
 | [`../powerman/README.md`](../powerman/README.md) | Cyclades PM10i PDU management via powerman on pfv-tsys1 | 2026-07-28 |
 | [`../console/README.md`](../console/README.md) | Serial console management (ser2net + conman) for 7 network switches on pfv-tsys4 | 2026-07-28 |
 | [`../k8s/README.md`](../k8s/README.md) | k3s cluster setup scripts: wipe, bootstrap, taint, verify (3-node HA over Tailscale) | 2026-07-28 |