test: add schema v3 only absence gate

.github/workflows/deployment.yml

@@ -24,6 +24,8 @@ jobs:
     name: LF, Compose, docs, and TypeScript
     runs-on: ubuntu-24.04
     timeout-minutes: 25
+    env:
+      PYTHONDONTWRITEBYTECODE: "1"
     steps:
       - name: Check out source
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -47,9 +49,13 @@ jobs:
           bash scripts/test-preprocess-compose-config.sh
           bash scripts/test-verify-workspace-install-docs.sh
           git diff --check
-      - name: Install backend dependencies
-        working-directory: backend
-        run: npm ci
+      - name: Assert clean checkout before release trust bootstrap
+        run: |
+          git diff --exit-code
+          git diff --cached --exit-code
+          test -z "$(git ls-files --others --exclude-standard)"
+      - name: Verify schema-v3-only release gate
+        run: bash scripts/verify-schema-v3-only-release.sh
       - name: Verify Task 13 clean-install and runtime fixtures
         run: |
           bash scripts/test-server-pi-state-topology.sh