Add AgentServices and x402 protocol

[vbkotecha]

What

This PR adds two entries:

1. AgentServices under AI & Agent Integrations — a production x402-paid data API platform for AI agents (54 services, 37 MCP tools, crypto/market/financial data via MCP and REST). agentservices.to

2. x402 under Related Protocols — the HTTP-native payment protocol using the 402 Payment Required status code, now under Linux Foundation governance (40 org members including AWS, Google, Visa, Mastercard, Stripe, Cloudflare). x402 is complementary to UCP — where UCP defines the commerce workflow, x402 enables the payment settlement for agent-initiated HTTP requests.

Why

• AgentServices is a live, production implementation of paid agent data APIs using x402 — directly relevant to the agentic commerce ecosystem this list curates.
• x402 fills a gap in the Related Protocols section alongside AP2 (Agent Payments Protocol). Both serve the payment layer of agent commerce.
• The x402 Foundation officially launched under Linux Foundation governance on Jul 14, 2026.

Verification

• AgentServices is live at agentservices.to with 54 services, 37 MCP tools, and 41 x402-paid endpoints.
• Listed on the official MCP Registry as to.agentservices/agentservices (v5.3.0).
• First x402 payment triggered and confirmed on Base mainnet (Jul 13, 2026).
• MCP handshake verified (protocol 2026-07-28).