BIOS sub-stage: switch to flag-file signaling, move push after W: copies

check-bios.cmd: drop literal `^` from BIOS_STATUS (caret survives quoted
SET so substring search for `->` never matched). Write X:\bios-fired.flag
on flash_done + staged paths so startnet.cmd can detect via if-exist.

startnet.cmd: replace `call set` substring-replace with `if exist
X:\bios-fired.flag`. Move push to after W:\Enrollment xcopy completes
(before Y: cleanup) so dashboard reflects "BIOS firmware update" stage
once file staging is done, matching user mental model of imaging order.

Tested flag-file logic in win11 VM cmd.exe: missing -> SKIPS, present
-> FIRES, removed -> SKIPS.

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

playbook/shopfloor-setup/BIOS/check-bios.cmd

@@ -110,7 +110,8 @@ exit /b 0
 
 :flash_done
 echo   BIOS update complete.
-set "BIOS_STATUS=%SYSMODEL% updated %BIOSVER% -^> %TARGETVER%"
+set "BIOS_STATUS=%SYSMODEL% updated %BIOSVER% to %TARGETVER%"
+echo flash_done %SYSMODEL% %BIOSVER% to %TARGETVER%> X:\bios-fired.flag
 exit /b 0
 
 :staged
@@ -121,7 +122,8 @@ echo     It will flash during POST after the
 echo     post-imaging reboot.
 echo   ========================================
 echo.
-set "BIOS_STATUS=%SYSMODEL% STAGED %BIOSVER% -^> %TARGETVER% (flashes on reboot)"
+set "BIOS_STATUS=%SYSMODEL% STAGED %BIOSVER% to %TARGETVER% (flashes on reboot)"
+echo staged %SYSMODEL% %BIOSVER% to %TARGETVER%> X:\bios-fired.flag
 exit /b 0
 
 :compare_versions