feat: add cross-platform customer fs generator

tools/customer_fs/build_windows.bat

@@ -0,0 +1,56 @@
+@echo off
+setlocal EnableExtensions
+
+set "SCRIPT_DIR=%~dp0"
+for %%I in ("%SCRIPT_DIR%..\..") do set "ROOT_DIR=%%~fI"
+
+if "%~1"=="" (
+    set "SOURCE_DIR=%ROOT_DIR%\audio_prompts\customer_fs"
+) else (
+    set "SOURCE_DIR=%~f1"
+)
+
+if "%~2"=="" (
+    set "OUTPUT_IMAGE=%ROOT_DIR%\output\customer_fs\customer_fs.bin"
+) else (
+    set "OUTPUT_IMAGE=%~f2"
+)
+
+set "TEMP_IMAGE=%OUTPUT_IMAGE%.tmp"
+set "MKLFS=%ROOT_DIR%\ql-cross-tool\win32\mklfs-v2.exe"
+set "PYTHON=%ROOT_DIR%\ql-cross-tool\win32\owtoolchain\Python\python.exe"
+
+if not exist "%MKLFS%" (
+    echo customer_fs generation failed: mklfs-v2.exe not found at "%MKLFS%"
+    exit /b 1
+)
+if not exist "%PYTHON%" (
+    echo customer_fs generation failed: bundled Python not found at "%PYTHON%"
+    exit /b 1
+)
+if not exist "%SOURCE_DIR%\" (
+    echo customer_fs generation failed: source directory not found at "%SOURCE_DIR%"
+    exit /b 1
+)
+
+for %%I in ("%OUTPUT_IMAGE%") do if not exist "%%~dpI" mkdir "%%~dpI"
+if exist "%TEMP_IMAGE%" del /q "%TEMP_IMAGE%"
+
+"%MKLFS%" -c "%SOURCE_DIR%" -s 589824 -i "%TEMP_IMAGE%"
+if errorlevel 1 goto :failed
+
+"%PYTHON%" "%SCRIPT_DIR%verify_customer_fs.py" ^
+    --image "%TEMP_IMAGE%" ^
+    --source "%SOURCE_DIR%"
+if errorlevel 1 goto :failed
+
+move /Y "%TEMP_IMAGE%" "%OUTPUT_IMAGE%" >nul
+if errorlevel 1 goto :failed
+
+echo customer_fs ready: "%OUTPUT_IMAGE%"
+exit /b 0
+
+:failed
+if exist "%TEMP_IMAGE%" del /q "%TEMP_IMAGE%"
+echo customer_fs generation failed; existing output was not changed.
+exit /b 1