Update security report email address

Update installation instructions in README.md

Fix contact email and update clone URL in CONTRIBUTING.md

Update link format in README.md

Fix link to agent folder in README

Update link format for agent folder in README

Update README.md

headers in README.md

updated README

Update Demo Repository link in README.md

fix: update status indicators in deliverables table in README

fix: update demo app reference in README and remove redundant emoji

feat: add student interaction, skill chains & doc saves to 19 agent skills

docs: rewrite Getting Started as visual Antigravity-centric guide

feat: add demo plugin reference for Antigravity agent