emmy.sci, publish library as Clerk notebooks

[sritchie]

• emmy.sci, publish library as Clerk notebooks #124:

  • Upgrades babashka/sci to 0.7.39.

  • Adds a working bb repl command to the repository.

  • Renames emmy.env.sci => emmy.sci, and adds an emmy.sci/install!
    command to make it easier to install all namespaces into a shared SCI
    context.

  • Renames context-opts in the new emmy.sci to emmy.sci/config, to match
    the sci-configs style.

  The full library is now published to https://emmy.mentat.org as a series of
  Clerk notebooks. This required a dependency on https://clerk-utils.mentat.org,
  but no actual Clerk dependency in the library.

[sritchie]

we don't need this yet, since none of the viewers are actually using Emmy code on the client side.