Add AgentPay Doc Tools

[noah-silver]

Adds one service entry to directory/apis.md (## Infrastructure APIs).

The 402 lives at the endpoint itself (unpaid GET returns an x402 v2 PAYMENT-REQUIRED challenge, Base eip155:8453 and Algorand), and at the /.well-known/x402 manifest linked in the entry.

Example:

GET https://agentpay-tools.agentpay-apis.workers.dev/tools/v1/pdf-text?url=https://arxiv.org/pdf/1706.03762

Docs: https://github.com/noah-silver/agentpay

[github-actions]

Gold-402 Verification: PASSED

URL checked: https://agentpay-tools.agentpay-apis.workers.dev/tools/v1/pdf-text?url=https://arxiv.org/pdf/1706.03762 (first url that is not a package, repo or social link)
Rule applied: service -- must answer HTTP 402
Result: endpoint returned HTTP 402 -- x402 compliant

This PR has been approved for merge. A maintainer will review and merge shortly.

---

Verified by Gold-402. Verification confirms x402 technical compliance only. It does not constitute endorsement of the service.

[github-actions]

Gold-402 Verification: PASSED

URL checked: https://agentpay-tools.agentpay-apis.workers.dev/tools/v1/pdf-text?url=https://arxiv.org/pdf/1706.03762 (first url that is not a package, repo or social link)
Rule applied: service -- must answer HTTP 402
Result: endpoint returned HTTP 402 -- x402 compliant

This PR has been approved for merge. A maintainer will review and merge shortly.

---

Verified by Gold-402. Verification confirms x402 technical compliance only. It does not constitute endorsement of the service.

[Haustorium12]

Knocked live 2026-10-04: GET /tools/v1/pdf-text → 402, x402 v2 exact, $0.01 USDC on Base with Algorand alongside. Merging as written. Thanks.