Final notice: release snapshot of Isabelle2025-1 tomorrow

[Makarius]

This is the last notice concerning the final release of Isabelle2025-1: RC4 
turned out a pretty good approximation, so everything is ready for liftoff, 
tomorrow 17-Dec-2025 approx. 11:00 Royal Bavarian Time.

It takes several hours to build everything, and afterwards 1-2 days until all 
mirrors are up-to-date. Then the announcement can be published on isabelle-users.



	Makarius