[ ProtocolSparkle/Sparkle-Protocol ] docs: Add CI/CD, architecture diagram, and Bundle Trading teaser - Add GitHub Actions CI workflow with Node.js 18/20 matrix - Add CI badge and Bitcoin/Taproot badge to README header - Add ASCII architecture diagram showing protocol flow - Add "Coming Soon: Bundle Trading" section - Add community links (Twitter, Discord placeholder) - Add CONTRIBUTING.md with contribution guidelines - Update Links section with GitHub repo link