ci(perf): Lighthouse CI on PR + main push

Gates on user-observed Web Vitals:
- accessibility >= 0.90 (ERROR if below — blocks)
- CLS <= 0.10 (ERROR — blocks)
- performance >= 0.80, LCP <= 2.5s, TBT <= 300ms (WARN — non-blocking)

Free temporary-public-storage uploads results; the URL is printed in
the CI log. Optional LHCI_GITHUB_APP_TOKEN enables PR-comment posting.

Author: bruAristimunha

.github/workflows/lighthouse.yml

@@ -0,0 +1,31 @@
+name: Lighthouse CI
+
+on:
+  pull_request:
+    branches: [main]
+  push:
+    branches: [main]
+  workflow_dispatch: {}
+
+env:
+  FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: 'true'
+
+jobs:
+  lighthouse:
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+      - run: npm ci
+
+      - name: Install Lighthouse CI
+        run: npm install --no-save @lhci/cli
+
+      - name: Run Lighthouse CI
+        run: npx lhci autorun --config=./.lighthouserc.cjs
+        env:
+          LHCI_GITHUB_APP_TOKEN: ${{ secrets.LHCI_GITHUB_APP_TOKEN }}

.lighthouserc.cjs

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+// .lighthouserc.cjs
+// Lighthouse CI config — runs against the local static server, gates
+// on Web Vitals budgets.
+
+module.exports = {
+  ci: {
+    collect: {
+      url: [
+        'http://localhost:8011/index.html?eeg=/test-data/edfplus-with-annotations.edf',
+      ],
+      startServerCommand: 'node scripts/serve.mjs 8011',
+      startServerReadyPattern: 'Static server listening',
+      numberOfRuns: 3,
+    },
+    assert: {
+      assertions: {
+        'categories:performance':  ['warn',  { minScore: 0.80 }],
+        'categories:accessibility':['error', { minScore: 0.90 }],
+        'categories:best-practices':['warn', { minScore: 0.85 }],
+        // Specific Web Vitals:
+        'largest-contentful-paint': ['warn',  { maxNumericValue: 2500 }],
+        'cumulative-layout-shift':  ['error', { maxNumericValue: 0.10 }],
+        'total-blocking-time':      ['warn',  { maxNumericValue: 300 }],
+      },
+    },
+    upload: {
+      target: 'temporary-public-storage',
+    },
+  },
+};