ci: 加入 PHP lint workflow

本 AddOn 是薄註冊層（bootstrap + 一個整合類別），無自有測試套件，
syntax lint 是此處有意義的 gate。

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

.gitea/workflows/test.yml

@@ -0,0 +1,20 @@
+name: Tests
+
+on:
+  push:
+    branches: [ main, master, develop ]
+  pull_request:
+    branches: [ main, master, develop ]
+
+jobs:
+  lint:
+    name: PHP Lint
+    runs-on: ubuntu-latest
+    # This AddOn is a thin registration shim (bootstrap + one integration class)
+    # with no test suite of its own; syntax lint is the meaningful gate here.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Check PHP syntax
+        run: |
+          find . -name "*.php" ! -path "./vendor/*" -print0 | xargs -0 -n1 php -l
+          echo "PHP syntax OK"