Add playwright E2E tests (#2174)

.github/workflows/build.yml

@@ -59,6 +59,49 @@ jobs:
       - name: Build C++ examples
         working-directory: photonlib-cpp-examples
         run: ./gradlew build
+  playwright-tests:
+    name: "Playwright E2E tests"
+    runs-on: ubuntu-22.04
+    needs: [validation]
+    steps:
+      # Checkout code.
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Fetch tags
+        run: git fetch --tags --force
+      - name: Install Java 17
+        uses: actions/setup-java@v4
+        with:
+          java-version: 17
+          distribution: temurin
+      - name: Install pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 10
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+      - name: Install mrcal deps
+        run: sudo apt-get update && sudo apt-get install -y libcholmod3 liblapack3 libsuitesparseconfig5
+      - name: Setup tests
+        working-directory: photon-client
+        run: |
+          pnpm install
+          pnpm test-setup
+      - name: Prebuild Gradle
+        run: ./gradlew photon-targeting:build photon-core:build photon-server:build -x check
+      - name: Run Playwright tests
+        working-directory: photon-client
+        run: pnpm test
+      - uses: actions/upload-artifact@v4
+        if: ${{ !cancelled() }}
+        with:
+          name: playwright-report
+          path: photon-client/playwright-report/
+          retention-days: 30
   build-gradle:
     name: "Gradle Build"
     runs-on: ubuntu-22.04