Fix initrd loading with explicit iPXE name binding

iPXE needs --name on the initrd command and initrd=<name> on the
kernel line to properly pass the initrd to the kernel. Without this,
the kernel never receives the initrd, causing VFS mount failure.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/pxe/ipxe.go

@@ -12,8 +12,11 @@ func BuildIPXEScript(publicURL string, img *model.Image, mac string) string {
 
 	return fmt.Sprintf(`#!ipxe
 echo Provisioning: booting %s on ${mac}
-kernel %s ramdisk_size=16777216 vga=791 video=vesafb:lfb:on rw quiet splash=verbose
-initrd %s
+echo Loading kernel...
+kernel %s ramdisk_size=16777216 vga=791 video=vesafb:lfb:on rw quiet splash=verbose initrd=initrd
+echo Loading initrd...
+initrd --name initrd %s
+echo Booting...
 boot
 `, img.Name, kernelURL, initrdURL)
 }