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>

.gitignore

@@ -24,3 +24,8 @@ Thumbs.db
 
 # Application specific
 *.pyc
+
+# PyInstaller
+build/
+dist/
+*.spec.bak