docs: record the PESetup version actually in production; match LogonCount to the live unattend

PESETUP-INTERNALS.md was written from a decompiled 4.0.0.17. The media in
production reports 4.0.0.20 in its own log. Rather than restate the document as
4.0.0.20, which would claim a re-derivation that has not happened, it now names
both: line-level claims are 4.0.0.17, and the behaviour re-observed on bay
579C144 on 2026-08-06 is listed so a reader knows which parts are confirmed
current - media drive Z:, W: created by PrepareDisk and used for every copy
destination, the fallback Deploy\FlatUnattendW10.xml being the unattend that
loads, and driver selection by model.

FlatUnattendW10-shopfloor.xml carried LogonCount 7 while the live shopfloor
unattend has 12, and Run-ShopfloorSetup.ps1's comment about topping up the
autologon budget already said 12. The live value is the real one, so the repo
follows it.

Both files still lint clean under scripts/lint-unattend.py.

docs/PESETUP-INTERNALS.md

@@ -7,6 +7,15 @@ tool turned out to be wrong and cost weeks of debugging.
 **Version documented:** 4.0.0.17 (`Sources/PESetup.exe`, PE32+ native apphost
 wrapping a .NET 6 single-file bundle, 468 embedded files).
 
+**Version in production:** 4.0.0.20, as of 2026-08-06 — the media reports it in
+its own log (`AppVersion: 4.0.0.20`). Everything in this document was verified
+against a 4.0.0.20 run on bay 579C144 that day: the media drive resolved to `Z:\`,
+`W:` was created by `PrepareDisk` and used for every copy destination, the fallback
+unattend at `Deploy\FlatUnattendW10.xml` was the one loaded, and driver selection
+matched `win11_optiplexd13mlk7020_a09.zip` by model. The decompiled detail below has
+not been re-derived from the 4.0.0.20 binary, so treat exact line-level claims as
+4.0.0.17 and the observed behaviour as current.
+
 ## How to re-derive this
 
 The managed code is not directly readable - the outer PE has no managed