Add missing Oanda, SGX and Cfd-InteractiveBrokers 2026 holidays to MHDB

[Marinovsky]

Description

Oanda and SGX have not yet published a complete 2026 Holiday schedule, just for New Year (https://www.sgx.com/trading , https://www.oanda.com/bvi-en/cfds/holiday-trading-hours/). Still, there was some wrong holidays in Forex-oanda-[*]. On the other hand, each IB CFD is part of the exchange SMART, which seems to be an special 'exchange' from IBKR, that searches the best prices for your orders on real exchanges such as Nasdaq, Nyse, etc. For that reason, I added the 2026 USA national holidays to Cfd-interactivebrokers-[*], following the pattern already present.

Related Issue

n/a

Motivation and Context

With this change the MHDB will keep updated

Requires Documentation Change

n/a

How Has This Been Tested?

n/a

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. Please add associated performance test and results)
• 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>

[Martin-Molinero]

Thank you 👍