docs: redesign README with enhanced formatting and structure

- Add centered header with badges for Python, Ollama, license, stars, and issues
- Replace plain text sections with emoji-prefixed headings throughout
- Add visual comparison table with emoji icons for feature categories
- Add note/tip/important callouts using GitHub-flavored markdown admonitions
- Reorganize table of contents with emoji prefixes and flattened structure
- Add numbered step headings in Quick Start section
- Add Contributing

Author: Web-Dev-Codi