fix: Replace PAUSE with message syntax (not supported in DOS 6.22)

Issue: DOS 6.22 PAUSE command does not accept message text as parameter.
The syntax "PAUSE message..." is a Windows NT/2000+ feature that causes
command-line parameters (%1, %2, etc.) to be consumed/lost in DOS 6.22.

Root cause: User ran "T:\DEPLOY.BAT TS-4R" but script reported
"Machine name not provided". The parameter %1 was being consumed by
the invalid PAUSE syntax at line 31 before reaching GET_MACHINE_NAME.

Changes:
- Fixed 46 PAUSE commands across 9 BAT files
- Converted "PAUSE message..." to "ECHO message..." + "PAUSE"
- Updated check-dos-compatibility.ps1 to detect PAUSE with message
- Created fix-pause-syntax.ps1 automated fix script

Example fix:
BEFORE (Windows NT+ syntax, causes parameter loss):
  PAUSE Press any key to continue...

AFTER (DOS 6.22 compatible):
  ECHO Press any key to continue...
  PAUSE

DOS 6.22 PAUSE command:
- Syntax: PAUSE (no parameters)
- Displays: "Press any key to continue..."
- Cannot customize message (built-in text only)

Files modified:
- DEPLOY.BAT: 10 PAUSE commands fixed
- UPDATE.BAT: 7 PAUSE commands fixed
- CTONW.BAT: 8 PAUSE commands fixed
- NWTOC.BAT: 6 PAUSE commands fixed
- REBOOT.BAT: 4 PAUSE commands fixed
- STAGE.BAT: 6 PAUSE commands fixed
- CHECKUPD.BAT: 2 PAUSE commands fixed
- DOSTEST.BAT: 2 PAUSE commands fixed
- AUTOEXEC.BAT: 1 PAUSE command fixed

Deployed to:
- D2TESTNAS: /data/test/*.BAT (9,908 bytes for DEPLOY.BAT)

Testing: Should now correctly receive command-line parameter:
  T:\DEPLOY.BAT TS-4R

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

STAGE.BAT

@@ -169,7 +169,8 @@ ECHO   4. Restore C:\AUTOEXEC.BAT from C:\AUTOEXEC.SAV
 ECHO.
 ECHO ==============================================================
 ECHO.
-PAUSE Press any key to return to DOS...
+ECHO Press any key to return to DOS...
+PAUSE
 GOTO END
 
 REM ==================================================================
@@ -186,7 +187,8 @@ ECHO   C:\CONFIG.NEW (not found)
 ECHO.
 ECHO Run NWTOC to download updates from network.
 ECHO.
-PAUSE Press any key to exit...
+ECHO Press any key to exit...
+PAUSE
 GOTO END
 
 :NO_AUTOEXEC
@@ -195,7 +197,8 @@ ECHO [ERROR] C:\AUTOEXEC.BAT not found
 ECHO.
 ECHO Cannot stage updates without existing AUTOEXEC.BAT
 ECHO.
-PAUSE Press any key to exit...
+ECHO Press any key to exit...
+PAUSE
 GOTO END
 
 :BACKUP_ERROR
@@ -208,7 +211,8 @@ ECHO Check:
 ECHO - Sufficient disk space on C:
 ECHO - C: drive is not write-protected
 ECHO.
-PAUSE Press any key to exit...
+ECHO Press any key to exit...
+PAUSE
 GOTO END
 
 :CREATE_ERROR
@@ -220,7 +224,8 @@ ECHO - C:\BAT directory exists
 ECHO - Sufficient disk space on C:
 ECHO - C: drive is not write-protected
 ECHO.
-PAUSE Press any key to exit...
+ECHO Press any key to exit...
+PAUSE
 GOTO END
 
 :MODIFY_ERROR
@@ -232,7 +237,8 @@ ECHO.
 ECHO Recovery:
 ECHO   COPY C:\AUTOEXEC.SAV C:\AUTOEXEC.BAT
 ECHO.
-PAUSE Press any key to exit...
+ECHO Press any key to exit...
+PAUSE
 GOTO END
 
 REM ==================================================================