fix(ci): deduplicate CI runs with concurrency group

When a PR targets develop, both push and pull_request triggers fire,
running every job twice. Add concurrency group keyed on PR number
(or ref for direct pushes) with cancel-in-progress to ensure only
one run per event.

Author: wazolab

.github/workflows/ci.yml

@@ -4,7 +4,11 @@ on:
   pull_request:
     branches: [develop, main]
   push:
-    branches: [develop]
+    branches: [develop, main]
+
+concurrency:
+  group: ci-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
 
 jobs:
   ci: