ci: add Lighthouse CI with performance/a11y/SEO budgets

Lighthouse CI runs on every PR against main. Budgets (category-level
scores, error-blocking unless noted):

  Performance:   >= 0.80 (baseline 0.89, desktop preset)
  Accessibility: >= 0.85 (baseline 0.89, color-contrast/labels flagged)
  Best Practices:>= 0.90 (baseline 1.00)
  SEO:           >= 0.95 (baseline 1.00)

Web Vitals as warnings (monitoring only, not blocking):
  LCP <= 2500ms, TBT <= 300ms, CLS <= 0.1

Setup:
- @lhci/cli, http-server, wait-on as devDependencies
- lighthouserc.json at repo root with desktop preset
- .github/workflows/lighthouse.yml: build → serve → lhci autorun
- Upload to temporary-public-storage (no LHCI server required)
- .lighthouseci/ gitignored

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: raifdmueller

.github/workflows/lighthouse.yml

@@ -0,0 +1,34 @@
+name: Lighthouse CI
+
+on:
+  pull_request:
+    branches: [main]
+
+jobs:
+  lhci:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build
+        run: npm run build
+
+      - name: Start static server
+        run: |
+          npx http-server dist -p 5000 --silent &
+          npx wait-on http://localhost:5000
+
+      - name: Run Lighthouse CI
+        run: npx lhci autorun
+        env:
+          LHCI_GITHUB_APP_TOKEN: ${{ secrets.LHCI_GITHUB_APP_TOKEN }}

.gitignore

@@ -15,3 +15,6 @@ Thumbs.db
 .vscode/
 *.swp
 *.swo
+
+# Lighthouse CI local results
+.lighthouseci/

lighthouserc.json

@@ -0,0 +1,26 @@
+{
+  "ci": {
+    "collect": {
+      "url": ["http://localhost:5000/"],
+      "numberOfRuns": 3,
+      "settings": {
+        "preset": "desktop",
+        "throttlingMethod": "simulate"
+      }
+    },
+    "assert": {
+      "assertions": {
+        "categories:performance": ["error", { "minScore": 0.8 }],
+        "categories:accessibility": ["error", { "minScore": 0.85 }],
+        "categories:best-practices": ["error", { "minScore": 0.9 }],
+        "categories:seo": ["error", { "minScore": 0.95 }],
+        "largest-contentful-paint": ["warn", { "maxNumericValue": 2500 }],
+        "total-blocking-time": ["warn", { "maxNumericValue": 300 }],
+        "cumulative-layout-shift": ["warn", { "maxNumericValue": 0.1 }]
+      }
+    },
+    "upload": {
+      "target": "temporary-public-storage"
+    }
+  }
+}