ci(cachix-pusher): Append cachix push workflow

.github/workflows/cachix-pusher.yml

@@ -0,0 +1,21 @@
+name: "cachix-pusher"
+
+on:
+  push:
+    branches:
+      - 'master'
+    tags:
+      - '*'
+
+jobs:
+  push:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: cachix/install-nix-action@v25
+      with:
+        nix_path: nixpkgs=channel:nixos-unstable
+    - uses: cachix/cachix-action@v14
+      with:
+        name: simula
+        signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'

.github/workflows/nix-checker.yml

@@ -4,6 +4,7 @@ on:
   pull_request:
   push:
     tags:
+      - '*'
     branches:
       - 'main'
 

flake.nix

@@ -348,7 +348,12 @@
 
           treefmt = {
             projectRootFile = "project.godot";
+
+            # Nix
             programs.nixfmt.enable = true;
+
+            # GitHub Actions
+            programs.actionlint.enable = true;
           };
 
           packages = {