ci: add CodeQL, Semgrep, Gitleaks, Trivy security scanning

.github/workflows/gitleaks.yml

@@ -0,0 +1,30 @@
+name: Secret Scanning (Gitleaks)
+
+on:
+  push:
+    branches: ['**']
+  pull_request:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  scan:
+    name: Scan for secrets
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0  # Full history for accurate scanning
+
+      - name: Install Gitleaks
+        run: |
+          curl -sSfL https://github.com/gitleaks/gitleaks/releases/download/v8.30.0/gitleaks_8.30.0_linux_x64.tar.gz | tar -xz
+          sudo mv gitleaks /usr/local/bin/
+
+      - name: Run Gitleaks
+        run: gitleaks detect --source . --config .gitleaks.toml --verbose