Add a visual onboarding journey

[mohsinht]

Summary

• add a complete docs/onboarding.md guide from fork to private deployment
• add lightweight animated terminal walkthroughs for setup, Prompt Studio, and Cloudflare deployment
• add a visual environment map showing where local settings, provider connections, variables, and secrets belong
• make the main README easier to scan with onboarding navigation and the new visuals
• clarify that the synthetic tutorial needs no .env, credentials, provider connection, or personal data

All visual content is synthetic and contains no private repository names, hostnames, credentials, or personal snapshots.

Validation

• Prettier formatting passed
• ESLint passed with zero warnings
• repository, privacy, data, and deployment validation passed
• 29 tests passed with required coverage
• tutorial retry check passed
• production build passed
• performance budgets passed at 83 KB JavaScript gzip, 8 KB CSS gzip, and 6 KB dashboard data gzip
• GIF animation and Markdown image references verified

The browser accessibility script could not run locally because this workspace has no Chromium or Chrome binary. GitHub CI will run the existing accessibility matrix in its standard environment.