Final 2024H2 blog post

[nikomatsakis]

We need to post a final update from 2024H2 indicating how far each project goal came towards completion.

Current draft on hackmd:

https://hackmd.io/uYEjOIudTZCEARfudVZc5A#

[nikomatsakis]

@davidtwco will do this.

[davidtwco]

rust-lang/blog.rust-lang.org#1457