implement applications.mastodon as a sample use-case of our data model

default.nix

@@ -9,6 +9,8 @@ let
     git-hooks
     gitignore
     ;
+  inherit (import sources.flake-inputs) import-flake;
+  inputs = (import-flake { src = ./.; }).inputs;
   inherit (pkgs) lib;
   inherit (import sources.flake-inputs) import-flake;
   inherit ((import-flake { src = ./.; }).inputs) nixops4;
@@ -76,6 +78,7 @@ in
   # re-export inputs so they can be overridden granularly
   # (they can't be accessed from the outside any other way)
   inherit
+    inputs
     sources
     system
     pkgs