Build add and edit contact form

[Gwani-28]

Summary

• scaffold a minimal Next.js app for Dead Simple CRM
• add /contacts/new for creating contacts and /contacts/[id]/edit for editing contacts
• include name, email, phone, company selector, tags, and notes fields
• validate required name, email, and company fields before saving a local CRM preview

Bounty

Shipyard bounty: bnt_QBfCyt0h - Build add and edit contact form.

Validation

• npm run typecheck
• npm run build
• npm audit --json returned zero vulnerabilities
• Browser checked create, edit, validation error, desktop, and mobile flows