feat: add TCP staging path for FreeDOS

fec/tcp-stage.bat

@@ -0,0 +1,19 @@
+@echo off
+rem Pull a host-built TCP staging bundle into the authoritative C:\FEC tree.
+rem QEMU user networking exposes the host as 10.0.2.2.  HTGET and UNZIP are
+rem supplied by the installed FreeDOS network tools.
+if "%1"=="" goto usage
+if exist C:\FEC\STAGE.ZIP del C:\FEC\STAGE.ZIP
+htget -o C:\FEC\STAGE.ZIP %1
+if errorlevel 1 goto fail
+unzip -o C:\FEC\STAGE.ZIP -d C:\FEC
+if errorlevel 1 goto fail
+if exist C:\FEC\TCPSTG.OK del C:\FEC\TCPSTG.OK
+echo OK>C:\FEC\TCPSTG.OK
+goto done
+:usage
+echo usage: TCP-STAGE.BAT http://10.0.2.2:8000/STAGE.ZIP
+goto done
+:fail
+echo FAIL>C:\FEC\TCPSTG.FAIL
+:done