feat: add hhu calendar

flake.nix

@@ -0,0 +1,22 @@
+{
+  description = "An api to provide static calender information";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs?ref=nixos-25.11";
+
+    blueprint = {
+      url = "github:numtide/blueprint";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
+    gomod2nix = {
+      url = "github:nix-community/gomod2nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  outputs = inputs: inputs.blueprint {
+    inherit inputs;
+    nixpkgs.overlays = [ inputs.gomod2nix.overlays.default ];
+  };
+}