Merge remote-tracking branch 'origin/pj/add-ci-checks' into staging

.forgejo/workflows/merge-main-check.yml

@@ -0,0 +1,26 @@
+name: merge-main-check
+on:
+  pull_request:
+    types:
+      - opened
+      - edited
+      - reopened
+      - synchronize
+
+defaults:
+  run:
+    shell: 'sh -e {0}'
+
+jobs:
+  check:
+    runs-on: shell
+    if: github.base_ref == 'main'
+    steps:
+      - name: Check if non-staging -> main
+        if: github.head_ref != 'staging'
+        run: echo 'Cannot merge non-staging branch to main'; exit 1
+
+      - name: Check if staging -> main
+        if: github.head_ref == 'staging'
+        run: echo 'Merge from staging branch to main allowed'; exit 0
+