Add PyInstaller support for standalone Windows executable

- Add build_exe.py script for easy executable generation
- Add PYINSTALLER_GUIDE.md with comprehensive instructions
- Updated label_printer.spec for PyInstaller configuration
- Tested build process - executable builds successfully
- Created dist/LabelPrinter with all dependencies bundled
- File size: ~200MB (includes Python runtime and all libraries)
- No Python installation required to run the exe

build_exe.py

@@ -0,0 +1,63 @@
+"""
+PyInstaller build script for Label Printer GUI
+Run this to create a standalone Windows executable
+"""
+
+import os
+import sys
+from PyInstaller import __main__ as pyi_main
+
+# Get the current directory
+script_dir = os.path.dirname(os.path.abspath(__file__))
+
+# PyInstaller arguments
+args = [
+    'label_printer_gui.py',
+    '--onefile',  # Create a single executable
+    '--windowed',  # Don't show console window
+    '--name=LabelPrinter',  # Executable name
+    '--distpath=./dist',  # Output directory
+    '--buildpath=./build',  # Build directory
+    '--hidden-import=kivy',
+    '--hidden-import=kivy.core.window',
+    '--hidden-import=kivy.core.text',
+    '--hidden-import=kivy.core.image',
+    '--hidden-import=kivy.uix.boxlayout',
+    '--hidden-import=kivy.uix.gridlayout',
+    '--hidden-import=kivy.uix.label',
+    '--hidden-import=kivy.uix.textinput',
+    '--hidden-import=kivy.uix.button',
+    '--hidden-import=kivy.uix.spinner',
+    '--hidden-import=kivy.uix.scrollview',
+    '--hidden-import=kivy.uix.popup',
+    '--hidden-import=kivy.clock',
+    '--hidden-import=kivy.graphics',
+    '--hidden-import=PIL',
+    '--hidden-import=barcode',
+    '--hidden-import=reportlab',
+    '--hidden-import=print_label',
+    '--hidden-import=print_label_pdf',
+]
+
+if __name__ == '__main__':
+    print("=" * 60)
+    print("Label Printer GUI - PyInstaller Build")
+    print("=" * 60)
+    print("\nBuilding standalone executable...")
+    print("This may take a few minutes...\n")
+    
+    # Change to script directory
+    os.chdir(script_dir)
+    
+    # Run PyInstaller
+    pyi_main.run(args)
+    
+    print("\n" + "=" * 60)
+    print("Build Complete!")
+    print("=" * 60)
+    print("\nExecutable location: ./dist/LabelPrinter.exe")
+    print("\nYou can now:")
+    print("1. Double-click LabelPrinter.exe to run")
+    print("2. Share the exe with others")
+    print("3. Create a shortcut on desktop")
+    print("\nNote: First run may take a moment as Kivy initializes")