fix(flake): expose Colmena executable directly

flake.nix

@@ -158,7 +158,9 @@
         };
       };
 
-      apps.${system}.colmena = inputs.colmena.apps.${system}.default // {
+      apps.${system}.colmena = {
+        type = "app";
+        program = lib.getExe inputs.colmena.packages.${system}.colmena;
         meta.description = "colmena";
       };