feat: add fade effects with API control and real-time event subscription
test: add API integration tests with isolated test environment and coverage reporting
build: update Makefile for recursive source finding, dynamic linking, and test targets
docs: document abstraction layer, fade effects, and API enhancements in README
feat: implement demo mode for automated feature showcase
feat: add XEmbed system tray protocol for external application icons
feat: add window snapping to left and right halves
feat: add minimize/restore toggle with Alt+F9 keybinding
docs: update README with new features and configuration details
build: update build system for new autostart and demo modules
