feat: Add storage skill, add OWS to wallets

[1a35e1]

Summary

• New storage/ skill — IPFS pinning, Arweave permanence, x402 payments for storage, ENS contenthash hosting
• OWS added to wallets/ — Open Wallet Standard for encrypted local wallet signing in agent workflows

Blind spots filled (🔴)

• LLMs don't know IPFS doesn't store files permanently (need pinning)
• LLMs don't know ENS websites use contenthash (EIP-1577), not URL text records
• LLMs don't know about x402 payments for storage (USDC inline with HTTP)
• LLMs don't know OWS exists — encrypted local wallets for CLI/agent signing
• LLMs use evm namespace for OWS, should be ethereum (changed in v1.2.4)
• LLMs don't know Infura IPFS was deprecated (Nov 2025)
• LLMs don't know web3.storage pivoted to Filecoin-only

Human needs to learn (🟣)

• Storage tier tradeoffs (CDN vs IPFS vs Arweave)
• How contenthash hosting works end-to-end
• OWS as a safer alternative to .env files for agent key management

🔗 Internal review before submitting upstream to austintgriffith/ethskills