OEM mode via Ctrl+C on the first screen, not a mode-picker entry

Restore the original screen order (keyboard first, then disk) and make Ctrl+C
on the keyboard screen the entry into OEM mode — the same hidden-Ctrl+C idiom
the disk-overwrite screen already uses for unencrypted installs. A confirm
guards against an accidental Ctrl+C; once confirmed, OEM jumps straight to
disk selection and the overwrite confirmation (no keyboard, no user), since
OEM is always a full-disk install. The 'OEM install' entry leaves the mode
picker. The harness drives the new path.

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

bin/omarchy-iso-test

@@ -606,46 +606,56 @@ audio-panel|meta_l-ctrl-a|omarchy-keyboard-panel|omarchy.audio'
 drive_configurator() {
   log "Driving the installer wizard"
 
-  # Disk first (the keyboard step moved after mode selection, and OEM skips it).
-  wait_for_screen "install disk" 300
-  capture_console "success-installer-01-install-disk"
-  press ret # the single virtio disk
-
-  # A blank disk shows the mode picker only when the bundled runtime supports
-  # OEM mode; otherwise the wizard goes straight to the overwrite confirm.
-  wait_for_screen "installation mode\|recovery possible" 60
-  if ocr_screen | grep -qi "installation mode"; then
-    capture_console "success-installer-02-install-mode"
-    if $OEM; then
-      press down # "OEM install" sits below "Full disk install" on a blank disk
-    fi
-    press ret
-  elif $OEM; then
-    capture_console "failure-installer-no-oem-choice"
-    echo "OEM flow requested but this ISO does not offer OEM mode" >&2
-    return 1
-  fi
-
-  wait_for_screen "recovery possible" 60
-  capture_console "success-installer-03-disk-warning-encrypted"
-  if ! $ENCRYPT; then
-    press ctrl-c # toggles the confirm to the unencrypted flow
-    wait_for_screen "without encryption" 30
-    capture_console "success-installer-04-disk-warning-unencrypted"
-  fi
-  press ret
+  # Keyboard is the first screen. Ctrl+C there is the hidden entry into OEM
+  # mode; a normal install just selects the layout.
+  wait_for_screen "keyboard layout" 300
+  capture_console "success-installer-01-keyboard-layout"
 
   if $OEM; then
-    # OEM installs skip the keyboard and user steps; the install starts now.
+    press ctrl-c # arm OEM mode
+    wait_for_screen "new owner" 30
+    capture_console "success-installer-02-oem-confirm"
+    press ret # "Yes, prepare for a new owner" is the affirmative default
+
+    # OEM jumps straight to disk selection, then the overwrite confirm.
+    wait_for_screen "install disk" 60
+    capture_console "success-installer-03-oem-install-disk"
+    press ret
+
+    wait_for_screen "recovery possible" 60
+    capture_console "success-installer-04-oem-disk-warning-encrypted"
+    if ! $ENCRYPT; then
+      press ctrl-c
+      wait_for_screen "without encryption" 30
+      capture_console "success-installer-05-oem-disk-warning-unencrypted"
+    fi
+    press ret
     sleep 2
     capture_console "success-installer-13-install-started"
     return 0
   fi
 
-  wait_for_screen "keyboard layout" 60
-  capture_console "success-installer-05-keyboard-layout"
   press ret # English (US) is preselected
 
+  wait_for_screen "install disk" 60
+  capture_console "success-installer-02-install-disk"
+  press ret # the single virtio disk
+
+  wait_for_screen "installation mode\|recovery possible" 60
+  if ocr_screen | grep -qi "installation mode"; then
+    capture_console "success-installer-03-install-mode"
+    press ret # "Full disk install" is preselected
+  fi
+
+  wait_for_screen "recovery possible" 60
+  capture_console "success-installer-04-disk-warning-encrypted"
+  if ! $ENCRYPT; then
+    press ctrl-c # toggles the confirm to the unencrypted flow
+    wait_for_screen "without encryption" 30
+    capture_console "success-installer-05-disk-warning-unencrypted"
+  fi
+  press ret
+
   wait_for_screen "Username" 120
   type_text "$GUEST_USER"
   capture_console "success-installer-06-username"