feat: add UCP JavaScript SDK

[artemii-karkusha]

Adds the UCP JavaScript SDK to the Utilities section.

What it is

The official JavaScript/TypeScript SDK for the Universal Commerce Protocol — runtime-validated Zod schemas and TypeScript types, auto-generated from the UCP JSON Schema spec. UCP is built on A2A (Agent2Agent) as one of its core transport bindings.

Coverage:

• Checkout, orders, payments, payment handlers, fulfillment
• Discounts, buyer consent, AP2 mandates
• Discovery profiles (platform & business), identity linking, catalog, cart
• All inline enums (15 standalone exports)

Features:

• 100% spec coverage — 100 schemas auto-generated from source
• Runtime validation via Zod — .parse() and .safeParse()
• Supports MCP, A2A, REST, and Embedded transport bindings
• Dual ESM/CJS build — works in Node.js and bundlers
• Available on npm as @omnixhq/ucp-js-sdk

Why it belongs here

UCP natively supports A2A as a transport binding. This SDK provides the TypeScript types and runtime validators needed to build A2A-compatible agentic commerce integrations.