chore: add devtools

nix/repo/soonix.nix

@@ -0,0 +1,38 @@
+{
+  inputs,
+  cell,
+  ...
+}: let
+  inherit (inputs) soonix;
+  inherit (cell) ci;
+in
+  (soonix.make {
+    hooks = {
+      ci = ci.soonix;
+      renovate = {
+        output = ".gitlab/renovate.json5";
+        data = {
+          extends = ["config:recommended"];
+          postUpgradeTasks = {
+            commands = [
+              "nix-portable nix run .#soonix:update"
+            ];
+            executionMode = "branch";
+          };
+          lockFileMaintenance = {
+            enabled = true;
+            extends = ["schedule:monthly"];
+            branchTopic = "lock-file-maintenance-{{packageFile}}";
+            commitMessageExtra = "({{packageFile}})";
+          };
+          nix.enabled = true;
+          gitlabci.enabled = false;
+        };
+        hook = {
+          mode = "copy";
+          gitignore = false;
+        };
+        opts.format = "json";
+      };
+    };
+  }).config