Remove GhostScript, use SumatraPDF only for printing

- Remove find_ghostscript() and print_pdf_with_ghostscript() from print_label.py
- SumatraPDF is now the primary print method with -print-settings noscale
- Fix SumatraPDF arg order: file_path moved to last position
- Add -appdata-dir so SumatraPDF reads conf/SumatraPDF-settings.txt (PrintScale=noscale)
- win32api ShellExecute kept as last-resort fallback
- Remove GhostScript bundling from LabelPrinter.spec and build_exe.py
- Add conf/ folder pre-flight check to build_exe.py
- Rebuild dist/LabelPrinter.exe (41 MB, SumatraPDF-only)

LabelPrinter.spec

@@ -63,7 +63,7 @@ a = Analysis(
         'print_label', 'print_label_pdf',
         'svglib', 'cairosvg',
         'watchdog', 'watchdog.observers', 'watchdog.events',
-        'pystray', 'win32timezone',
+        'pystray', 'win32api', 'win32print', 'win32timezone',
     ],
     hookspath=[],
     hooksconfig={},