Add conditional BIOS-update sub-stage on idx=1

winpe-status-push.ps1 now accepts -CurrentStage / -StageIndex
params so callers can override the default "WinPE: PESetup / WIM
apply" string. Backwards compatible.

startnet.cmd: after the existing initial WinPE status push,
inspect $BIOS_STATUS for the "->" marker that check-bios.cmd
writes when an update was actually applied or staged. If present,
fire a second idx=1 push with stage="WinPE: BIOS firmware update -
<status>". No-op for clean "up to date" / "no update in catalog"
runs.

imaging.html: at stage_idx=1 with "bios" in current_stage, swap
friendly label to "Updating BIOS firmware" with a do-NOT-power-off
hint. Bays without firmware updates show the default "Booting from
PXE" label as before.

boot.wim startnet.cmd updated via wimupdate so live PXE clients
pick it up at next boot.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

webapp/templates/imaging.html

@@ -63,6 +63,12 @@ window.addEventListener('DOMContentLoaded', scheduleImagingReload);
   {% set is_done = s.status == 'succeeded' %}
   {% set border = 'danger' if is_failed else ('success' if is_done else 'primary') %}
   {% set friendly = stage_labels.get(stage_idx, ('Stage ' ~ stage_idx, '')) %}
+  {# Stage 1 sub-phase: if WinPE pushed a BIOS update stage string,    #}
+  {# show a BIOS-specific friendly label. Otherwise default idx=1.     #}
+  {% if stage_idx == 1 and s.current_stage and 'bios' in s.current_stage|lower %}
+    {% set friendly = ('Updating BIOS firmware',
+        'WinPE detected a firmware update for this model. Do NOT power off until the next reboot. Imaging continues afterward.') %}
+  {% endif %}
   {# Stage 7 fans out by sub-phase. Monitor pushes different stage     #}
   {# strings as it crosses each Phase 1-4 boundary. Swap friendly      #}
   {# label based on which keyword shows up.                            #}