winpe: externalize WinPE-phase status push to scripts/winpe-status-push.ps1

The inline one-liner in startnet.cmd called Get-NetAdapter, which is
not available in WinPE's stripped PowerShell (no NetTCPIP module).
Errors silently swallowed by the surrounding try/catch - POST never
fired, dashboard never showed bays during the WIM-apply phase.

Externalize to a standalone .ps1 on the enrollment share:

  * Uses wmic (always present in WinPE 10+) for both serial AND mac
    instead of Get-CimInstance / Get-NetAdapter.
  * Logs every step to X:\Windows\Temp\winpe-status-push.log so a
    future "POST didn't fire" debug is one file read away.
  * startnet.cmd now just runs powershell -File Y:\scripts\winpe-status-
    push.ps1. Future edits to the push logic do NOT require a boot.wim
    rebuild; just edit the .ps1 on the share.

Mirror the existing pattern for run-enrollment.ps1 / wait-for-internet.ps1
/ migrate-to-wifi.ps1 (all already at /srv/samba/enrollment/scripts/).
Add the new file to the playbook's enrollment-scripts copy loop.

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

playbook/pxe_server_setup.yml

@@ -404,6 +404,7 @@
         - { src: "{{ usb_mount }}/shopfloor-setup/run-enrollment.ps1", dest: "run-enrollment.ps1" }
         - { src: "{{ usb_mount }}/wait-for-internet.ps1",              dest: "wait-for-internet.ps1" }
         - { src: "{{ usb_mount }}/migrate-to-wifi.ps1",                dest: "migrate-to-wifi.ps1" }
+        - { src: "{{ usb_mount }}/winpe-status-push.ps1",              dest: "winpe-status-push.ps1" }
       ignore_errors: yes
 
     - name: "Deploy site-config.json to config/"