Gentoo Ebuild builds

Automatically generate and maintain Gentoo ebuild files for all packages.

Guaranteed usable source tarballs are in the respective Apt repos:
- https://apertium.projectjj.com/apt/nightly/source/
- https://apertium.projectjj.com/apt/release/source/

For language and pair packages, provide both source and binary ebuilds.

Start by reviewing the nightly and release source package listings in the respective Apt repositories linked in the issue. Determine the package set and how language and pair packages should be represented as source and binary ebuilds. Done means Gentoo ebuilds are automatically generated and maintained for all packages, with both variants provided where requested.

Written by the indexing model from the issue text.