Renumber PXE LAN from 10.9.100.0/24 to 172.16.9.0/24

Single-site bay-stuck issue at WJ: GE Intune Report IP script filters
Get-NetIPAddress on StartsWith("10.") and posts everything matching
to the GE Tines webhook. Bays at WJ get the PXE LAN 10.9.100.x IP
captured and reported -> GE backend tags bays as on a non-corp 10.x
subnet -> dynamic group eligibility for SFLD policy never matches.
Other GE sites work because their PXE LANs aren't on 10.x at all.

Renumber PXE LAN to RFC1918 172.16.9.0/24 so the GE filter naturally
skips wired PXE addresses without any disable-NIC dance.

Server-side already in flight (netplan dual-bound, dnsmasq scope +
boot URL repointed, blancco preferences + grub.cfg + iPXE GetPxeScript
all sed'd to 172.16.9.1). This commit is the playbook / scripts /
docs side: 109 hits across 35 files sed'd in one shot.

After this lands + boot.wim is rebuilt + bays renumber off DHCP,
the 10.9.100.1 binding will be dropped from netplan as the final
cleanup step.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/download-drivers.py

@@ -31,7 +31,7 @@ import xml.etree.ElementTree as ET
 from pathlib import Path
 
 REPO_DIR = Path(__file__).resolve().parent
-PXE_HOST = "10.9.100.1"
+PXE_HOST = "172.16.9.1"
 PXE_USER = "pxe"
 PXE_PASS = "pxe"
 UPLOAD_DEST = "/home/pxe/image-upload"
@@ -715,7 +715,7 @@ def main():
             concurrent.futures.wait(futures)
 
         # --- Download BIOS (goes to shared winpeapps dir, read by check-bios.cmd
-        # in WinPE phase via \\10.9.100.1\winpeapps\_shared\BIOS\). Playbook
+        # in WinPE phase via \\172.16.9.1\winpeapps\_shared\BIOS\). Playbook
         # task at pxe_server_setup.yml:485 deploys check-bios.cmd + Flash64W.exe
         # to this same directory. ---
         bios_ok = bios_err = 0