HDHP and HSA

My husband retired in July 2021.  We continue to be covered on his former employer's HDHP.  My husband will turn 65 in December 2025 and begin Medicare coverage.  What is the amount we can contribute to our HSA for 2025?  Also will I still be able to contribute to the HSA for me until I turn 65 in 2028?  Will the HSA transfer to me when my husband turns 65.  I will still be eligible for his company's HDHP until I turn 65.