docs: Add beginner-friendly installation guides

- QUICK-START.md: 3-step visual guide for quick setup
- EASY-INSTALL.md: Detailed step-by-step guide with troubleshooting
- TROUBLESHOOTING.md: Common problems and solutions with examples
- Updated main README to reference all guides

These guides are written for users with limited technical experience,
using simple language, clear steps, and visual indicators.