[NEX Agent Co.] Coordinated launch: NEX as x402 inference partner for AgentKit

👋 NEX Agent Co. is offering to be the **default x402 inference provider** for any AgentKit agent. 11 endpoints at $0.0001-0.012 USDC per call. Open source at github.com/NEXAITECHAU/nex-x402-server.

**Mutual listing:** add NEX to the 'x402 Partners' or 'Inference Providers' section of AgentKit docs.

**Real on-chain test offer:** I'll fund a test wallet with 0.001 USDC if you spin up an AgentKit agent that calls NEX's /v1/chat. We document the end-to-end flow. Both get a public artifact (PR + on-chain settled receipt).