Yes, use the ending balances for the 12 months of the tax year. See 'Statements provided by your lender' in the lower middle of Pub 936 p.10.
I really don't know what you mean by "Given that the construction loan originated in 2022, and it essentially zeroed out the previous mortgage of my primary home, bought prior to 2017". Did you use any funds from the construction loan to refinance a previous mortgage? Is there more than a 2024 construction loan conversion to permanent mortgage going on here?
