Network model, IPAM, interface layouts and the region/rack split (MAAS-style)

- fabrics, VLANs, subnets, IP ranges (dynamic/reserved/static), IPAM with adoption of
  addresses machines already have; rollcall fabric|vlan|subnet|range|ip
- interface layouts (physical/bond/vlan, NICs by selector: boot, name, mac, fastest:N, ib:N)
  per machine or per tag; deployment allocates addresses and writes cloud-init network-config
  plus udev name rules (RHEL cloud images boot with net.ifnames=0); release frees them;
  rollcall layout, rollcall net show|set
- region/rack: rollcall rack long-polls its desired state (per-MAC PXE files kept in the
  database, dnsmasq configuration and host files) and a BMC command queue, caches boot and OS
  images (kernels/initrds prefetched for TFTP), proxies the node API and tags requests with its
  name; the region runs an embedded rack controller; install-rack.sh, rollcall-rack.service
- dnsmasq configuration generated per rack from the VLANs it serves (split pool for two racks);
  reload script restarts only on change and restores the last working config if dnsmasq does
  not come back (drilled in the lab)
- web: Network page, per-machine network tab, layout action, tag layout; console: Network page,
  network section in the machine view, layout action
- tests for candidates, plans (default, bond+VLAN, pinned, DHCP fallback), network-config,
  udev rules and dnsmasq rendering
- lab: pve-vbmc address script finds the interface per BMC address

Verified in the lab: embedded rack (10.213.77.0/24) and a remote rack controller on a second
SDN segment (10.213.78.0/24): enlistment, commissioning, BMC through the rack's queue, image
cache, deployment and phone-home through the rack; Debian 13, Ubuntu 24.04 and Rocky 9 with a
static boot NIC and with an active-backup bond carrying VLAN 200.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

deploy/rack.example.json

@@ -0,0 +1,12 @@
+{
+  "name": "hall-b",
+  "region": "http://10.0.0.234",
+  "secret": "<rack_secret from the region's config.json>",
+  "url": "http://10.213.78.1",
+  "listen": "10.213.78.1:80",
+  "tftp_root": "/srv/tftp",
+  "dnsmasq_dir": "/var/lib/rollcall/dnsmasq",
+  "cache_dir": "/var/cache/rollcall",
+  "ipmitool": "ipmitool",
+  "dhcp_interfaces": []
+}