test(auth): gate local and OIDC authentication release

.github/workflows/deployment.yml

@@ -74,6 +74,38 @@ jobs:
           npx vitest run
           npx tsc -b
 
+  authentication-browser:
+    name: Hermetic authentication browser gate
+    needs: deterministic
+    runs-on: ubuntu-24.04
+    timeout-minutes: 30
+    steps:
+      - name: Check out source
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+      - name: Set up Node.js
+        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
+        with:
+          node-version: "24.16.0"
+          package-manager-cache: false
+      - name: Set up Go
+        uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0
+        with:
+          go-version: "1.26.5"
+          cache-dependency-path: tools/tht/go.sum
+      - name: Install backend dependencies
+        working-directory: backend
+        run: npm ci
+      - name: Install frontend dependencies
+        working-directory: frontend
+        run: npm ci
+      - name: Install Chromium for Playwright
+        working-directory: frontend
+        run: npx playwright install --with-deps chromium
+      - name: Run authentication browser smoke
+        run: bash scripts/authentication-smoke.sh
+
   linux-docker:
     name: Linux Docker deployment and rollback
     runs-on: ubuntu-24.04