Add standalone application build support

- Add MSMD.spec PyInstaller configuration file
- Update README.md with comprehensive build instructions for macOS, Windows, and Linux
- Update .gitignore to exclude PyInstaller build artifacts (build/, dist/)
- Successfully tested macOS .app bundle (92 MB)

Users can now build platform-specific executables without requiring Python installation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

MSMD.spec

@@ -0,0 +1,90 @@
+# -*- mode: python ; coding: utf-8 -*-
+
+import sys
+from pathlib import Path
+
+block_cipher = None
+
+# Collect data files (config and icons)
+datas = [
+    ('config.ini', '.'),
+]
+
+# Add icon files if they exist
+for icon in ['MSMD32.png', 'refresh.png', 'settings.png']:
+    if Path(icon).exists():
+        datas.append((icon, '.'))
+
+a = Analysis(
+    ['MSMD_multiLevel.py'],
+    pathex=[],
+    binaries=[],
+    datas=datas,
+    hiddenimports=[
+        'PyQt5',
+        'PyQt5.QtCore',
+        'PyQt5.QtGui',
+        'PyQt5.QtWidgets',
+        'serial',
+        'serial.tools.list_ports',
+        'pyautogui',
+        'pyaudio',
+        'wave',
+    ],
+    hookspath=[],
+    hooksconfig={},
+    runtime_hooks=[],
+    excludes=[],
+    win_no_prefer_redirects=False,
+    win_private_assemblies=False,
+    cipher=block_cipher,
+    noarchive=False,
+)
+
+pyz = PYZ(a.pure, a.zipped_data, cipher=block_cipher)
+
+exe = EXE(
+    pyz,
+    a.scripts,
+    [],
+    exclude_binaries=True,
+    name='MSMD',
+    debug=False,
+    bootloader_ignore_signals=False,
+    strip=False,
+    upx=True,
+    console=False,  # No console window on launch
+    disable_windowed_traceback=False,
+    argv_emulation=False,
+    target_arch=None,
+    codesign_identity=None,
+    entitlements_file=None,
+)
+
+coll = COLLECT(
+    exe,
+    a.binaries,
+    a.zipfiles,
+    a.datas,
+    strip=False,
+    upx=True,
+    upx_exclude=[],
+    name='MSMD',
+)
+
+# macOS App Bundle
+app = BUNDLE(
+    coll,
+    name='MSMD.app',
+    icon=None,  # Set to 'MSMD.icns' if you have a macOS icon file
+    bundle_identifier='com.msmd.player',
+    info_plist={
+        'NSPrincipalClass': 'NSApplication',
+        'NSHighResolutionCapable': 'True',
+        'CFBundleShortVersionString': '1.2.4',
+        'CFBundleVersion': '1.2.4',
+        'CFBundleName': 'MSMD Player',
+        'CFBundleDisplayName': 'MSMD Player',
+        'LSMinimumSystemVersion': '10.13.0',
+    },
+)