Add scheduled supply-chain watch workflow

.github/workflows/supply-chain-watch.yml

@@ -0,0 +1,57 @@
+name: Supply-Chain Watch
+
+on:
+  schedule:
+    - cron: '17 */6 * * *'
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: false
+
+permissions:
+  contents: read
+
+jobs:
+  ioc-watch:
+    name: IOC watch
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+
+      - name: Setup Node.js
+        uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
+        with:
+          node-version: '20.x'
+
+      - name: Install dependencies without lifecycle scripts
+        run: npm ci --ignore-scripts
+
+      - name: Verify registry signatures and advisories
+        run: |
+          npm audit signatures
+          npm audit --audit-level=high
+
+      - name: Validate IOC scanner fixtures
+        run: node tests/ci/scan-supply-chain-iocs.test.js
+
+      - name: Generate IOC report
+        run: |
+          mkdir -p artifacts
+          node scripts/ci/scan-supply-chain-iocs.js --json > artifacts/supply-chain-ioc-report.json
+
+      - name: Validate workflow hardening rules
+        run: node scripts/ci/validate-workflow-security.js
+
+      - name: Upload IOC report
+        if: always()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: supply-chain-ioc-report
+          path: artifacts/supply-chain-ioc-report.json
+          retention-days: 14