Add CodeQL workflow for security analysis

Author: armanist

.github/workflows/codeql.yml

@@ -0,0 +1,30 @@
+name: CodeQL
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  schedule:
+    - cron: '0 0 * * 1' # weekly
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@v3
+        with:
+          languages: php  # explicitly set PHP here
+
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@v3