Limit Order fixes

[dkuthoore]

Summary

This PR addresses the remaining review comments from #20:
(1) enforce the price limit predicate in validateToolCalls before approving swaps;
(2) enforce the SMA predicate in the SMA variant;
(3) set the hydration lock only after a successful ProposalExecuted log fetch so failed fetches are retried. It also adds a validity guard for SMA and price data in the limit-order-sma agent.

Changes

1. Enforce limit predicate (limit-order)

• agent-library/agents/limit-order/agent.js: Added LIMIT_PRICE_USD = 2000 and a price check in validateToolCalls before validated.push. Fetches ethPriceUSD via Chainlink (with CoinGecko fallback) and throws if ethPriceUSD > LIMIT_PRICE_USD.

2. Enforce SMA predicate (limit-order-sma)

• agent-library/agents/limit-order-sma/agent.js: In validateToolCalls, before validated.push, fetches ethPriceUSD and smaEth200USD from fetchEthPriceDataFromCoinGecko() and throws if ethPriceUSD > smaEth200USD. Adds a validity guard that throws if smaEth200USD or ethPriceUSD is null, undefined, or not finite before the comparison.

3. Defer hydration lock until log fetch succeeds

• agent-library/agents/limit-order/agent.js and agent-library/agents/limit-order-sma/agent.js: In reconcileProposalSubmission, moved hydratedFromChain = true from before the getLogs call to after it (inside the try block). If getLogs throws, hydration is not marked complete and the next poll retries.