add official Gitea Actions test cases (quickstart/checkout/contexts)

.gitea/workflows/official-checkout.yml

@@ -0,0 +1,24 @@
+# 官方用例 2: actions/checkout@v4 官方 Action 深度验证
+# 覆盖: 官方 action 在 Gitea 的兼容性 / 私有仓 clone 认证(GITHUB_TOKEN) / 内容与 commit 完整性
+name: Official Action - checkout
+on: [push]
+
+jobs:
+  checkout:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: verify workspace content
+        run: |
+          set -e
+          echo "workspace=$GITHUB_WORKSPACE"
+          ls -la
+          test -f README.md || { echo "FAIL: README.md not found"; exit 1; }
+          echo "OK: repository checked out"
+      - name: verify commit info
+        run: |
+          set -e
+          test -n "$GITHUB_SHA" || { echo "FAIL: GITHUB_SHA empty"; exit 1; }
+          echo "sha=$GITHUB_SHA"
+          git log -1 --oneline
+          git rev-parse HEAD | grep -q "^${GITHUB_SHA}" && echo "OK: HEAD matches GITHUB_SHA"