[Michealshodipo56]

Summary

• add GitBook-ready public documentation covering architecture, usage, deployment, security, and submission evidence
• add a restrictive Content Security Policy alongside existing security headers
• configure GitBook to publish from the docs directory

Verification

• lint passed
• typecheck passed
• 15 tests passed
• production dependency audit reports 0 vulnerabilities
• local production build reached compilation but the host ran out of disk space; required GitHub CI is the authoritative clean build