treewide: yet another restructure

modules, overlays, and packages have their own default.nix re-exporting
things instead of reading file paths. slightly improves declarativeness.

wine-osu is removed; we're just using nix-gaming (for now).

our custom packages will now have to be accessed via pkgs.me instead of
just pkgs. helps know where it came from

future goals: get rid of our overlays completely, or at least not make
it replace anything from nixpkgs

modules/user/packages-rin.nix

@@ -32,7 +32,7 @@
         inputs.who-reacted
       ];
       themes = [
-        pkgs.discord-tokyonight
+        pkgs.me.discord-tokyonight
         inputs.radialstatus
         inputs.tokyonight
         inputs.zelk