ci(security): add Trivy filesystem vulnerability scan

.github/workflows/trivy.yml

@@ -0,0 +1,39 @@
+name: Trivy security scan
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  security-events: write
+
+jobs:
+  scan:
+    name: Trivy filesystem scan
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Run Trivy filesystem scan
+        uses: aquasecurity/trivy-action@0.36.0
+        with:
+          scan-type: fs
+          scan-ref: .
+          severity: HIGH,CRITICAL
+          ignore-unfixed: true
+          format: sarif
+          output: trivy-results.sarif
+          exit-code: "1"
+
+      # Always upload SARIF so findings show in the Security tab even when
+      # the previous step fails the job (exit-code: 1 on findings).
+      - name: Upload Trivy results to GitHub Security tab
+        if: always()
+        uses: github/codeql-action/upload-sarif@v3.35.2
+        with:
+          sarif_file: trivy-results.sarif
+          category: trivy-fs