feat(explorer): mission-control resilience, ops token labels, and CI validate

Add SSE reconnect with backoff, fallback REST polling, visibility-aware refresh,
extended token-list labels on operations pages, validate-on-pr workflow, and smoke coverage.

Co-authored-by: Cursor <cursoragent@cursor.com>

.gitea/workflows/validate-on-pr.yml

@@ -0,0 +1,70 @@
+name: Validate Explorer
+
+on:
+  pull_request:
+    branches: [main, master]
+    paths:
+      - '.gitea/workflows/validate-on-pr.yml'
+      - 'frontend/**'
+      - 'scripts/e2e-*.spec.ts'
+      - 'package.json'
+      - 'package-lock.json'
+      - 'playwright.config.ts'
+  push:
+    branches: [main, master]
+    paths:
+      - '.gitea/workflows/validate-on-pr.yml'
+      - 'frontend/**'
+      - 'scripts/e2e-*.spec.ts'
+      - 'package.json'
+      - 'package-lock.json'
+      - 'playwright.config.ts'
+
+jobs:
+  frontend:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: frontend
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: npm
+          cache-dependency-path: frontend/package-lock.json
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Lint, type-check, and unit tests
+        run: npm test
+
+  smoke-e2e:
+    runs-on: ubuntu-latest
+    needs: frontend
+    if: github.event_name == 'push'
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: npm
+          cache-dependency-path: package-lock.json
+
+      - name: Install root dependencies
+        run: npm ci
+
+      - name: Install Playwright browser
+        run: npx playwright install chromium
+
+      - name: Run live sprint smoke tests
+        env:
+          EXPLORER_URL: https://explorer.d-bis.org
+        run: npm run e2e -- scripts/e2e-sprint-smoke.spec.ts