ci: add .drone.yml

.drone.yml

@@ -0,0 +1,25 @@
+kind: pipeline
+type: docker
+name: clang format
+
+trigger:
+  branch:
+  - main
+
+steps:
+- name: clang format
+  image: clang_format:latest
+  commands:
+    - |
+      set -e
+      clang-format --version
+
+      find ./modules -name '*.?pp' | while read -r file; do
+        echo "Checking format for $file"
+        if ! clang-format --dry-run --Werror "$file"; then
+          echo "❌ Formatting issue detected in $file"
+          exit 1
+        fi
+      done
+
+      echo "✅ All files are properly formatted"