ci: add workflow_dispatch and concurrency settings to prevent duplicate runs

Author: Polliog

.github/workflows/ci.yml

@@ -5,6 +5,12 @@ on:
     branches: [main, develop]
   pull_request:
     branches: [main, develop]
+  workflow_dispatch:
+
+# Prevent duplicate runs on the same branch/PR
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.ref_name }}
+  cancel-in-progress: true
 
 env:
   NODE_VERSION: '20'