ci: add AgentShield security scan workflow

.github/workflows/security-scan.yml

@@ -0,0 +1,35 @@
+name: AgentShield Security Scan
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+# Prevent duplicate runs
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+# Minimal permissions
+permissions:
+  contents: read
+
+jobs:
+  agentshield:
+    name: AgentShield Scan
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20.x'
+
+      - name: Run AgentShield security scan
+        run: npx ecc-agentshield scan --path . --min-severity medium --format terminal
+        continue-on-error: true  # Informational only — ECC contains intentional config examples