feat: add Open Wallet Standard signer adapter

[njdawn]

Summary

• Adds @x402/signer-ows, a new package that adapts Open Wallet Standard wallets for use with x402
• Supports both EVM and SVM (Solana) chains — any OWS-compatible wallet can sign x402 payments
• Includes unit tests for both EVM and SVM signers

Test plan

• pnpm test passes in typescript/packages/signer-ows
• pnpm build succeeds
• Verify EVM signer correctly signs EIP-712 typed data via OWS wallet
• Verify SVM signer correctly signs Solana transactions via OWS wallet

🤖 Generated with Claude Code

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

[vercel]

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