feat: implement Self-Trade Prevention (STP)

[fasenderos]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/fasenderos/nodejs-order-book/blob/main/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs (README.md) have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

User can trade against themself

Related Issues: #537, #226 and #149

What is the new behavior?

Implements Self-Trade Prevention (STP) as described in Binance's STP documentation. Orders from the same account (accountId) can now be prevented from matching each other based on the taker's stpMode.

What's included

New API (SelfTradePreventionMode enum):

• NONE — no prevention (default, backward compatible)
• EXPIRE_MAKER — resting maker order(s) expire, taker continues
• EXPIRE_TAKER — taker expires immediately, maker stays on book
• EXPIRE_BOTH — both maker and taker expire

New fields on all order types:

• accountId?: string — identifies the account/trade group for STP matching
• stpMode?: SelfTradePreventionMode — STP mode for the order

New response field (IProcessOrder):

• stpExpired?: IOrder[] — orders removed from the book due to STP

New error:

• ERROR.STP_TRIGGERED (code 1202) — returned when EXPIRE_TAKER or EXPIRE_BOTH reject the taker

Scenarios covered (16 test cases):

• EXPIRE_MAKER with limit and market orders
• EXPIRE_TAKER with limit and market orders
• EXPIRE_BOTH with limit and market orders
• Taker mode wins over maker mode (per Binance spec)
• Mixed accounts at same price level (STP only applies to matching account)
• Multi-price-level STP expiration
• NONE mode (same account matching allowed)
• IOC orders with STP
• STP carried through triggered stop orders
• Backward compatible when no accountId is set

Fixes

Closes #537

Does this PR introduce a breaking change?

• Yes
• No

Other information

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (5e241ea) to head (8b59b53).

Additional details and impacted files

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  Coverage   100.00%   100.00%            
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  Files           10        10            
  Lines         2369      2538   +169     
  Branches       303       350    +47     
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+ Hits          2369      2538   +169     

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