fix(docs): update stale Basenames and x402 links

[Osraka]

Summary

• update stale Basenames redirect destinations to the current Wagmi Basenames integration page
• update the stale x402 payment redirect to the current Pay for APIs & Services page
• fix the same stale Basenames link in the Basenames FAQ

Context

This addresses part of #1426. I intentionally left the /apps/quickstart/create-new-app redirects out of this PR because #1427 already covers those, and left /get-started/migrate-from-onchainkit alone because the current replacement destination is less clear from the existing docs structure.

Validation

• git diff --check
• node -e "JSON.parse(require('fs').readFileSync('docs/docs.json','utf8'))"
• verified the new destination files exist:
  • docs/base-account/framework-integrations/wagmi/basenames.mdx
  • docs/ai-agents/payments/pay-for-services-with-x402.mdx

[cb-heimdall]

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