chore(lib/treewide): cleanup directory struture of lib. See lib/readme.md for details

lib/inventory/frontmatter/interface.nix

@@ -0,0 +1,86 @@
+{
+  lib,
+  specialArgs,
+  ...
+}:
+let
+  inherit (lib) mkOption types;
+in
+{
+  options = {
+    description = mkOption {
+      type = types.str;
+      description = ''
+        A Short description of the module.
+      '';
+    };
+    categories = mkOption {
+      default = [ "Uncategorized" ];
+      description = ''
+        Categories are used for Grouping and searching.
+
+        While initial oriented on [freedesktop](https://specifications.freedesktop.org/menu-spec/latest/category-registry.html) the following categories are allowed
+      '';
+      type = types.listOf (
+        types.enum [
+          "AudioVideo"
+          "Audio"
+          "Video"
+          "Development"
+          "Education"
+          "Game"
+          "Graphics"
+          "Social"
+          "Network"
+          "Office"
+          "Science"
+          "System"
+          "Settings"
+          "Utility"
+          "Uncategorized"
+        ]
+      );
+    };
+    features = mkOption {
+      default = [ ];
+      description = ''
+        Clans Features that the module implements support for.
+
+        !!! warning "Important"
+            Every ClanModule, that specifies `features = [ "inventory" ]` MUST have at least one role.
+            Many modules use `roles/default.nix` which registers the role `default`.
+
+            If you are a clan module author and your module has only one role where you cannot determine the name, then we would like you to follow the convention.
+      '';
+      type = types.listOf (
+        types.enum [
+          "experimental"
+          "inventory"
+        ]
+      );
+    };
+
+    constraints = mkOption {
+      default = { };
+      description = ''
+        Constraints for the module
+
+        The following example requires exactly one `server`
+        and supports up to `7` clients
+
+        ```md
+        ---
+        constraints.roles.server.eq = 1
+        constraints.roles.client.max = 7
+        ---
+        ```
+      '';
+      type = types.submoduleWith {
+        inherit specialArgs;
+        modules = [
+          ../constraints
+        ];
+      };
+    };
+  };
+}