Implement agent-cli (#1–#42)

[joeblau]

Implements the agent-cli roadmap (#43) with one commit per issue, made with Codex. Build, lint, typecheck and tests pass locally (38 files, 71 tests).

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Partial (left open)

• Privy wallet policies: trade-only, never withdraw #11 Privy policy only sees the L1 action hash, so it can't check each order's size or value. The no-withdraw limit relies on Hyperliquid agent permissions plus local checks.
• SKILL.md for Claude Code / Codex #37 SKILL.md is complete, but no agent has run it against real testnet yet (needs Testnet end-to-end test suite #39 credentials).
• Testnet end-to-end test suite #39 The mocked end-to-end suite passes. The real testnet run needs testnet credentials/secrets in CI.
• Global install: npm i -g and Bun #40 Global npm/Bun install works locally. Installing from the npm registry needs a published package.
• Release pipeline (changesets, npm publish, binaries, provenance) #41 The release pipeline is in place. Publishing needs npm credentials (NPM_TOKEN / provenance setup).