Redefine package set on top of overlays I wanted to reduce duplication, but ended up somewhat in the same place (with manifest.nix). Yet I find it much more elegant.
ci.nix: Fix patched package list generation The core of the fix is importing ./patches with the extended package set. The rest is just trying to keep the same structure (no flattening) while filtering out functions (`packagesFor` and the like).
ci: Add Nix expression with all possible package configurations The new ci.nix, when passed to nix-build: 1. runs the lib tests; 2. builds new packages when imported directly from ./pkgs; 3. builds new packages from the overlay; 4. builds patched packages from the overlay. These should uncover issues in the direct-overlay translation, which we'll need before consolidating */default.nix and */overlay.nix. I don't think we'll support loading the patched packages directly, moving forward.