Second review pass: strip account fields, clear stale cidata inputs, await OEM finalization

Codex xhigh round 2:

- Strip account authentication fields (!users, !root-password,
  root_enc_password, auth_config account entries) from the archinstall config
  in OEM mode, not just user_credentials — a combined/legacy config could
  otherwise have archinstall create a provisioning account before OOBE.
- Clear stale OEM inputs (oem marker, credentials, optional files) from /root
  before copying a cidata drive, so a retried install in the same live session
  can't force a fresh drive back into OEM mode or reuse an old LUKS passphrase.
- The test harness waits for the OEM pending flag to clear before saving the
  base image, so it never snapshots a half-finalized first boot; it also
  handles the deliberately skipped mode picker on blank disks built against a
  pre-OEM runtime.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

configs/airootfs/usr/local/bin/omarchy-cidata-load

@@ -38,10 +38,20 @@ done
 mkdir -p "$mnt"
 mount -o ro "$device" "$mnt" || exit 1
 
+# Clear any inputs a previous load in this live session left in /root before
+# copying the current drive: a stale `oem` marker or credentials file would
+# otherwise force a fresh drive's config back into OEM mode or hand it an old
+# LUKS passphrase. The interactive wizard writes these same names, but a
+# cidata load always precedes it, so nothing of the user's is discarded here.
+optional_inputs=(user_credentials.json oem user_full_name.txt user_email_address.txt user_encrypt_installation.txt authorized_keys tailscale_authkey)
+for file in user_configuration.json "${optional_inputs[@]}"; do
+  rm -f "$dest/$file"
+done
+
 loaded=1
 if [[ -f $mnt/user_configuration.json ]] && [[ -f $mnt/user_credentials.json || -f $mnt/oem ]]; then
   files=("$mnt"/user_configuration.json)
-  for file in user_credentials.json oem user_full_name.txt user_email_address.txt user_encrypt_installation.txt authorized_keys tailscale_authkey; do
+  for file in "${optional_inputs[@]}"; do
     [[ -f $mnt/$file ]] && files+=("$mnt/$file")
   done
   if cp "${files[@]}" "$dest"/; then