feat: add Lighthouse CI for quality scoring

.github/workflows/build.yml

@@ -5,6 +5,9 @@ on:
     branches:
       - main
 
+permissions:
+  contents: read
+
 jobs:
   build:
     runs-on: ubuntu-latest

.github/workflows/lighthouse.yml

@@ -0,0 +1,40 @@
+name: Lighthouse CI
+
+on:
+  pull_request:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+jobs:
+  lighthouse:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "22.12.0"
+          cache: npm
+          cache-dependency-path: astro-site/package-lock.json
+
+      - name: Install dependencies
+        working-directory: astro-site
+        run: npm ci
+
+      - name: Create assets symlink
+        run: mkdir -p astro-site/src/content && ln -s ../../../assets astro-site/src/content/assets
+
+      - name: Build site
+        working-directory: astro-site
+        run: npm run build
+
+      - name: Lighthouse CI
+        uses: treosh/lighthouse-ci-action@v12
+        with:
+          configPath: ./lighthouserc.json
+          uploadArtifacts: true

lighthouserc.json

@@ -0,0 +1,21 @@
+{
+  "ci": {
+    "collect": {
+      "staticDistDir": "./astro-site/dist",
+      "url": [
+        "/",
+        "/introduction/",
+        "/building-blocks/",
+        "/branching-and-merging/"
+      ]
+    },
+    "assert": {
+      "assertions": {
+        "categories:performance": ["warn", { "minScore": 0.9 }],
+        "categories:accessibility": ["error", { "minScore": 0.9 }],
+        "categories:best-practices": ["warn", { "minScore": 0.9 }],
+        "categories:seo": ["warn", { "minScore": 0.9 }]
+      }
+    }
+  }
+}