Add GitHub Action for Unlighthouse site scan

This workflow automates site performance and budget checks using Unlighthouse. It builds the SvelteKit preview, runs assertions, generates reports, and uploads them for further analysis.

Author: sandroguras

.github/workflows/unlighouse.yml

@@ -0,0 +1,47 @@
+name: Unlighthouse Site Scan
+on: [push]
+
+jobs:
+  unlighthouse-site-scan:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 1
+
+      - name: Setup Bun
+        uses: oven-sh/setup-bun@v2
+
+      - name: Install Dependencies
+        run: bun install -g @unlighthouse/cli puppeteer
+
+      - name: Build SvelteKit Preview
+        run: make build
+
+      # Run build in background and log output
+      - name: Start Preview Server
+        run: |
+          bun run preview --port 4173 &
+          echo "Waiting for preview to start on port 4173…"
+          bunx wait-on http://localhost:4173
+
+      - name: Run Unlighthouse Assertions & Generate Static Report
+        run: |
+          unlighthouse-ci \
+            --site http://localhost:4173 \
+            --budget 75 \
+            --upload.target=lhci \
+            --upload.serverBaseUrl=https://lhci-server-crimson-bush-1151.fly.dev \
+            --upload.token=${{ secrets.LHCI_BUILD_TOKEN }}
+
+      - name: Upload Unlighthouse Report
+        uses: actions/upload-artifact@v4
+        if: ${{ !cancelled() }}
+        with:
+          name: unlighthouse-report
+          path: .unlighthouse/**/*
+          include-hidden-files: true
+          retention-days: 30