[x402 catalog slot #226] Build x402 Embedding Generation API behind pay-gate

RAG backbone — every retrieval burns one embedding. Compounding revenue. Endpoints: embed, bulk embed, multi-model, similarity, models. Wrap OpenAI/Cohere/Voyage or self-host sentence-transformers.

WHY: $5 bounty is setup. Real reward = you OWN the deployed API. Every x402 agent calling your endpoint pays YOUR Base wallet in USDC. No revenue share with us.

FULL SPEC, ENDPOINTS, ACCEPTANCE CRITERIA, REFERENCE YAML, BUILD DOCS:

https://gist.github.com/pay-skill/22cb20f89afa29e53e16990663cc6005

Submission: HTTPS URL of your API + your Base wallet address + one paid round-trip showing 402 -> 200 with real data. Verifier checks pay request returns 402 with valid x402 headers, paid request returns real data, pay discover finds it, info blocks filled per endpoint, no fake/static responses.

settlement: "tab" required (micropayments — direct settlement requires $1+/call which doesn't fit this catalog).