instead of f5 and blockade; idea is breakthrough with Pawns
46. Nf3 Nba7
if King goes to stop white Pawns,then Pb7 is lost
threat is gxh6 and then bringing Knight to g4
If Black tries waiting policy than White can manouver his Rook so as to either capture Pb7 or infiltrate into Black soft belly through g-file.
The end position is a fortress.
For the last time, you could have won with 57. Ra4 instead of trading knights.
Your main positional mistake in the endgame was that you closed the entire king side.
As rightly observed, h5 instead of g5 should have been better.