test,ci: 建立 phpunit 基建 + 移植 WC 測試 + CI workflow

- composer.json / phpunit.xml / tests/bootstrap.php（比照 HP AddOn，
  直接 require 核心 plugin 的 unit bootstrap）
- tests/unit/WooCommerceIntegrationTest.php（自 A 移植，10 tests）
- .gitea/workflows/test.yml：lint + unit（unit job 會一併 checkout 核心 plugin，
  因為測試 bootstrap 依賴它）

10 tests / 33 assertions GREEN

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TbG1keQQ7XBa7qMQY16KCY

.gitea/workflows/test.yml

@@ -0,0 +1,46 @@
+name: Tests
+
+on:
+  push:
+    branches: [ main, master, develop ]
+  pull_request:
+    branches: [ main, master, develop ]
+
+jobs:
+  lint:
+    name: PHP Lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Check PHP syntax
+        run: |
+          find . -name "*.php" ! -path "./vendor/*" ! -path "./tests/*" -print0 | xargs -0 -n1 php -l
+          echo "PHP syntax OK"
+
+  unit:
+    name: Unit Tests
+    runs-on: ubuntu-latest
+    # The suite boots off the core plugin's test bootstrap, so the core must be
+    # checked out next to this AddOn under wp-content/plugins/.
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          path: 2meet-data-optimizer-woocommerce-addon
+
+      - name: Checkout core plugin
+        uses: actions/checkout@v4
+        with:
+          repository: wpdev/2meet-data-optimizer
+          path: 2meet-data-optimizer
+
+      - name: Install dependencies
+        working-directory: 2meet-data-optimizer-woocommerce-addon
+        run: composer install --no-interaction --prefer-dist
+
+      - name: Install core dev dependencies (test bootstrap needs them)
+        working-directory: 2meet-data-optimizer
+        run: composer install --no-interaction --prefer-dist
+
+      - name: Run unit tests
+        working-directory: 2meet-data-optimizer-woocommerce-addon
+        run: php vendor/bin/phpunit --configuration phpunit.xml --testdox