Wax/Trace triad: arrow-key bay picker + S: backup path

Two operator-UX improvements for the Backup / Export / Install triad.

1. Backup target moves from \\tsgwp00525\...\formtracepac to S:\2 WJ Scans
   Record Retention\backup\waxtrace\<asset>\. S: is mapped at shopfloor
   imaging time and stays mapped post-categorization, so the same default
   path works whether the operator runs the backup on an old bay (manual
   pre-image capture) or a freshly imaged one. The destination directory
   is created if missing.

2. New Select-WaxtraceAsset.ps1 - arrow-key bay picker patterned after
   the WinPE select-waxtrace-asset.ps1. Reads bay-config.csv (sibling
   file), shows asset_tag + ftpak_version + model + user_id per row, and
   returns the selected asset_tag via stdout. Falls back to a manual
   entry prompt if the CSV is missing or the operator picks "Other".

   Backup / Export / Install now invoke the picker when interactive AND
   bay-config.csv is alongside the script. Non-interactive paths
   (qga / SYSTEM / scheduled task) keep silently defaulting to
   COMPUTERNAME so unattended runs are unchanged.

   Export gained an -AssetNumber parameter and stamps it into the output
   CSV filename so multiple inventories from the same host stay
   distinguishable when the operator is auditing several bays in a row.

bay-config.csv is copied into the scripts\ dir so the picker has a
source of truth that ships next to the scripts (and into pxe-images
for tech distribution).

Smoke tested on win11 VM: all four PS1 parse-clean, non-interactive
backup path still produces a valid ZIP (silent COMPUTERNAME default),
picker handles missing-CSV gracefully (manual-entry fallback). The
arrow-key UX itself is operator-verifiable only on a real terminal.

playbook/shopfloor-setup/gea-shopfloor-waxtrace/scripts/bay-config.csv

@@ -0,0 +1,16 @@
+asset_tag,ftpak_version,model,user_id
+WJF00159,6.103,AVANT,3974839712
+WJRP3689,5.510,CV-4500,3744284509
+WJRP2660,6.0,CV-4500,2365986521
+WJRP2659,6.0,CV-4500,2709054503
+WJF00545,6.213,AVANT,3878777362
+WJRP3638,5.602,CV-4500,0720778210
+WJF00052,6.103,AVANT,3270314998
+WJF00084,6.103,AVANT,1476212857
+WJF00083,6.103,AVANT,2934506987
+WJRP3025,6.0,CV-3200,2292822471
+WJF00197,6.104,AVANT,1191612605
+WJRP4802,6.002,AVANT,0920866935
+WJRP2347,6.0,CV-4500,3585172946
+WJRP2035,6.0,CV-4500,2292822471
+WJRP2335,6.0,CV-4500,1780916688