Add inst.ks.sendmac to the iPXE boot script

Cobbler's per-MAC gPXE script passed inst.ks.sendmac, making anaconda send
its interface MACs as X-RHN-Provisioning-MAC-N headers when fetching the
kickstart. bootapi's iPXE script omitted it, so the boot script was not a
full drop-in for Cobbler's gpxe output.

- Emit inst.ks.sendmac immediately before inst.ks= in the boot iPXE template,
  matching Cobbler ordering.
- Assert the arg is present in the rendered catalog iPXE test.

Claude-Session: https://claude.ai/code/session_01JUoARVdmhxKQHyyyp1pxeT

internal/render/render_test.go

@@ -136,7 +136,7 @@ func TestRenderIPXECatalog(t *testing.T) {
 	mustContain(t, s, "kernel "+artifactBase+"/almalinux/9/BaseOS/x86_64/os/images/pxeboot/vmlinuz")
 	mustContain(t, s, "initrd "+artifactBase+"/almalinux/9/BaseOS/x86_64/os/images/pxeboot/initrd.img")
 	mustContain(t, s, "inst.repo="+artifactBase+"/almalinux/9/BaseOS/x86_64/os")
-	mustContain(t, s, "inst.ks=http://bootapi.example.net/ks/web01")
+	mustContain(t, s, "inst.ks.sendmac inst.ks=http://bootapi.example.net/ks/web01")
 	mustContain(t, s, "inst.text") // catalog kernel arg
 	mustContain(t, s, "net.ifnames=0")
 }

templates/ipxe/boot.ipxe.tmpl

@@ -6,12 +6,14 @@ it. Mirrors how Cobbler generated a per-MAC gPXE script carrying inst.ks=.
 
 KernelURL/InitrdURL/RepoURL come from the selected catalog entry (artifactapi
 remote); KernelArgs are the catalog's extra args. KickstartURL uses
-BOOTAPI_BASE_URL (http://).
+BOOTAPI_BASE_URL (http://). inst.ks.sendmac makes anaconda send its interface
+MACs as X-RHN-Provisioning-MAC-N headers when fetching the kickstart (Cobbler
+parity; lets /ks resolve a host by MAC as well as by name).
 */ -}}
 #!ipxe
 echo bootapi: provisioning {{ .FQDN }} ({{ .Platform }})
 {{ if and .KernelURL .InitrdURL -}}
-kernel {{ .KernelURL }} initrd=initrd.img{{ if .RepoURL }} inst.repo={{ .RepoURL }}{{ end }} inst.ks={{ .KickstartURL }} ip=dhcp{{ range .KernelArgs }} {{ . }}{{ end }}
+kernel {{ .KernelURL }} initrd=initrd.img{{ if .RepoURL }} inst.repo={{ .RepoURL }}{{ end }} inst.ks.sendmac inst.ks={{ .KickstartURL }} ip=dhcp{{ range .KernelArgs }} {{ . }}{{ end }}
 initrd {{ .InitrdURL }}
 boot
 {{- else -}}