Add v3 payout-wallet keygen + bind-at-create-key helper

[epanonymous]

Summary

• Add generatePayoutWallet() for local Bitplanet v3 ed25519 keypair generation, returning base58 pubkey and secret material.
• Bind generated payout pubkeys during agent registration by default while returning the generated secret only to the SDK caller.
• Support external/passkey wallet binding via a caller-supplied payoutWallet.pubkey, payoutWallet.publicKey, or payout_pubkey.
• Update the manual publish dry-run path to use npm pack --dry-run, avoiding failures on already-published package versions.

Dependency note

• Adds tweetnacl for small offline ed25519 key generation and bs58 for base58 encoding.

Validation

• npm test
• npm run build
• CJS import smoke test for generatePayoutWallet()
• GitHub Actions Publish to NPM dry-run: https://github.com/Deva-me-AI/deva-agent-sdk/actions/runs/27679830635

[epanonymous]

Closing — superseded by #10 (lazy auto-generate + bind on first API call). #9 implemented the registration-time / bind-at-create-key (G7) model, which is the up-front-wallet path we abandoned in favor of the frictionless lazy bind. See #10.

[epanonymous]

Closed as incorrect / superseded — this is the old up-front "bind the payout wallet when you create the key" (G7) approach, which was killed in favor of lazy auto-bind. Use #10 (wallet auto-binds silently on first API call) instead. Head branch deleted. (GitHub doesn't allow deleting PRs, only closing — leaving this note so it doesn't mislead.)