Generalize the base image from audit mode, with hibernation off

The answer file now boots into audit mode after Setup instead of logging on
as the built-in Administrator with a password: no account or credentials in
the answer file, and no copy of one left in C:\Windows\Panther. The auditUser
commands disable the built-in Administrator, turn hibernation off (no
hiberfil.sys in the image), remove cached answer files and setup logs, and run
sysprep /generalize.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

build-windows-base.sh

@@ -6,13 +6,14 @@
 # made once, and this script needs nothing outside this directory:
 #   1. an answer ISO is built from windows11/seed/Autounattend.xml;
 #   2. QEMU installs Windows unattended from the ISO into a scratch directory.
-#      After the first logon, the answer file runs sysprep /generalize, which
-#      removes the machine identity and shuts the guest down;
+#      The answer file then boots into audit mode, where it runs sysprep
+#      /generalize, which removes the machine identity and shuts the guest down;
 #   3. the shut-down disk is converted into the output file and made read-only.
 # The image holds nothing but Windows itself, like a cloud image: no VirtIO or
 # other hardware-specific drivers (the installation hardware, windows11/qemu,
 # only uses devices with inbox Windows drivers), no machine identity, no user
-# account (the built-in Administrator is disabled), no SSH, no settings. Every
+# account (the answer file holds no credentials either: audit mode needs no
+# account; the built-in Administrator is disabled), no SSH, no settings. Every
 # VM is configured on its first boot: Windows looks for an Unattend.xml in the
 # root of an attached CD-ROM during its specialize and OOBE passes, and so
 # takes the host name, account, auto logon, SSH and so on from a seed ISO.