Add cachix-push app

Author: locallycompact

nix/cachix-push.nix

@@ -0,0 +1,14 @@
+{ self, ... }: {
+  perSystem = { pkgs, ... }: {
+    apps.cachix-push = {
+      type = "app";
+      program = "${pkgs.writeShellApplication {
+        name = "cachix-push";
+        meta.description = "Build all flake outputs and push them to cachix.";
+        text = ''
+          ${pkgs.omnix}/bin/om ci run ${self} | cachix push cardano-scaling
+        '';
+      }}/bin/cachix-push";
+    };
+  };
+}