feat(polymarket): add buildOnly mode for unsigned transactions - Fixes #53

[theluckystrike]

Summary

This PR adds a buildOnly parameter to CreateOrderParams that enables a "build only" mode for the Polymarket exchange. When buildOnly is set to true, the order is created and signed but NOT submitted to the network. Instead, the signed order data is returned, allowing users to:

• Sign and broadcast the transaction themselves
• Route the transaction through an on-chain middleware contract
• Use non-custodial integrations

Changes

1. core/src/types.ts: Added buildOnly?: boolean to CreateOrderParams interface
2. core/src/exchanges/polymarket/index.ts: Modified createOrder to check for buildOnly flag:
   • When buildOnly is true: calls client.createOrder() which builds and signs the order but does NOT submit it, returns the order with status pending
   • When buildOnly is false (default): behaves as before, submits the order via createAndPostOrder()

Usage Example

const order = await client.createOrder({
  marketId: ...,
  outcomeId: ...,
  side: buy,
  type: market,
  amount: 100,
  buildOnly: true  // Returns signed order without submitting
});
// order.status === pending
// Use order.id (orderHash) for your own signing/broadcasting flow

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Contributed by theluckystrike | Zovo — Chrome Extension Studio

[realfishsam]

Why did you close this? I was going to merge it into the latest changes and credit you as a co-author! Please reopen, and I will do so!