chore: scaffold docs repo — structure, tooling, and getting started guide

[basanth-p]

Summary

Set up the docs repo as the public developer documentation site for Patch ID.

Proposed structure

docs/
  getting-started/
    introduction.md
    quick-start.md
    authentication.md
  api-reference/
    score.md
    signals.md
    webhooks.md
  guides/
    integrate-hiring-platform.md
    integrate-dao.md
    embed-score-widget.md
  partner/
    overview.md
    rate-limits.md
    pricing.md

Tooling options

• Mintlify (recommended — dev-native, clean)
• Nextra (Next.js-based)
• Docusaurus

Priority

P1 — needed before API beta.