test(e2e): add MVP end-to-end automation suite and CI workflow (#713)

* test(e2e): add mvp playwright suite and PR workflow

* ci(e2e): use JDK 21 for kkFileView build

.github/workflows/pr-e2e-mvp.yml

@@ -0,0 +1,93 @@
+name: PR E2E MVP
+
+on:
+  pull_request:
+    branches: [master]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  e2e-mvp:
+    runs-on: ubuntu-latest
+    timeout-minutes: 40
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup JDK 21
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '21'
+          cache: maven
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+          cache-dependency-path: tests/e2e/package-lock.json
+
+      - name: Install LibreOffice
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libreoffice
+
+      - name: Build kkFileView
+        run: mvn -q -pl server -DskipTests package
+
+      - name: Install E2E deps
+        working-directory: tests/e2e
+        run: |
+          npm install
+          npx playwright install --with-deps chromium
+
+      - name: Generate fixtures
+        run: node tests/e2e/scripts/generate-fixtures.mjs
+
+      - name: Start fixture server
+        run: |
+          cd tests/e2e/fixtures
+          python3 -m http.server 18080 > /tmp/fixture-server.log 2>&1 &
+
+      - name: Start kkFileView
+        run: |
+          JAR_PATH=$(ls server/target/kkFileView-*.jar | head -n 1)
+          nohup env KK_TRUST_HOST='*' KK_NOT_TRUST_HOST='10.*,172.16.*,192.168.*' java -jar "$JAR_PATH" > /tmp/kkfileview.log 2>&1 &
+
+      - name: Wait for services
+        run: |
+          for i in {1..60}; do
+            curl -fsS http://127.0.0.1:18080/sample.txt >/dev/null && break
+            sleep 1
+          done
+          for i in {1..120}; do
+            curl -fsS http://127.0.0.1:8012/ >/dev/null && break
+            sleep 1
+          done
+
+      - name: Run E2E
+        working-directory: tests/e2e
+        env:
+          KK_BASE_URL: http://127.0.0.1:8012
+          FIXTURE_BASE_URL: http://127.0.0.1:18080
+        run: npm test
+
+      - name: Upload Playwright report
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: playwright-report
+          path: tests/e2e/playwright-report
+
+      - name: Upload service logs
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: e2e-service-logs
+          path: |
+            /tmp/kkfileview.log
+            /tmp/fixture-server.log