fix: add EAD future-option expiry definition

[Romazes]

Description

Adds an EAD (Euro/Australian Dollar Cross Rate) entry to FuturesOptionsExpiryFunctions so the FOP expires per CME spec - the second Friday prior to the third Wednesday of the contract month - instead of falling back to the underlying future's quarterly (HMUZ) expiry.

CME contract spec: https://www.cmegroup.com/markets/fx/cross-rates/euro-fx-australian-dollar.contractSpecs.options.html

Related PR(s)

N/A

Related Issue

N/A

Motivation and Context

Motivation and Context

CME lists EAD futures only on quarterly months (Mar/Jun/Sep/Dec), but lists EAD options on those quarters plus 3 serial months. Lean had no EAD entry in _futuresOptionExpiryFunctions, so the FOP expiry fell back to the future's rule, which rolls any non-quarterly month forward to the next quarter. The serial EADN6 (Jul) and the quarterly EADU6 (Sep) ended up with the same expiry and strike, so they became the same Lean Symbol.

The AlgoSeek converter then failed when both tars were processed on the same trade date:

AlgoSeekFuturesConverter.Convert(): Exception caught! File: /raw/futureoption/usa/20260428/EAD/EADU6.tar 
Err: AlgoSeekFuturesProcessor(): file clash detected: 
/temp-output-directory/futureoption/cme/minute/ead/202609/20260428_trade_american/20260428_ead_minute_trade_american_put_16400000_20260914.csv

CME spec — Euro/Australian Dollar (EUR/AUD) Monthly Options:

Listed Contracts: Quarterly contracts (Mar, Jun, Sep, Dec) listed for 4 consecutive quarters and serial contracts listed for 3 consecutive months

Termination of Trading: Trading terminates at 9:00 a.m. CT on the second Friday prior to the third Wednesday of the contract month.

Requires Documentation Change

No.

How Has This Been Tested?

Verified with two new MapsCorrectly cases in Lean.DataSource.AlgoSeekFutures AlgoSeekFuturesOptionsReaderTest:

• EADU6 P1640 (Sep 2026, quarterly) -> FOP expiry 2026-09-04, underlying U6 future expires 2026-09-14.
• EADN6 P1640 (Jul 2026, serial) -> FOP expiry 2026-07-02 (Jul 3 is observed Independence Day, shifted back one business day), underlying rolls to U6.

Both resolve to distinct Lean Symbols, confirming the file clash is gone.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves implementation)
• Performance (non-breaking change which improves performance)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Non-functional change (xml comments/documentation/etc)

Checklist:

• My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My branch follows the naming convention bug-<issue#>-<description> or feature-<issue#>-<description>