fix(ci): 修复preview cleanup的PR号提取和SSH安装问题

- PR号提取改用GITHUB_EVENT_PATH优先，兼容closed事件
- SSH安装增加预检测，支持更多包管理器(apk/apt/yum/dnf)
- 修复comment步骤同样的PR号提取问题

.gitea/workflows/preview-cleanup.yml

@@ -19,7 +19,19 @@ jobs:
       shell: sh
       run: |
         set -eu
-        PR_NUMBER=$(echo "$GITHUB_REF" | sed 's|refs/pull/||; s|/.*||')
+        # 优先从event payload中读取（兼容所有PR事件类型）
+        if [ -n "${GITHUB_EVENT_PATH:-}" ] && [ -f "$GITHUB_EVENT_PATH" ]; then
+          PR_NUMBER=$(python3 -c "import json,sys; print(json.load(sys.stdin).get('number',''))" < "$GITHUB_EVENT_PATH")
+        fi
+        # fallback: 从GITHUB_REF中提取
+        if [ -z "${PR_NUMBER:-}" ]; then
+          PR_NUMBER=$(echo "$GITHUB_REF" | sed -n 's|refs/pull/\([0-9]*\)/.*|\1|p')
+        fi
+        # 再fallback: 兼容纯数字ref
+        if [ -z "${PR_NUMBER:-}" ] || ! echo "$PR_NUMBER" | grep -qE '^[0-9]+$'; then
+          echo "WARNING: Could not extract PR number cleanly, using raw ref suffix"
+          PR_NUMBER=$(echo "$GITHUB_REF" | sed 's|refs/pull/||; s|/.*||')
+        fi
         echo "PR_NUMBER=$PR_NUMBER" >> $GITHUB_ENV
         echo "PR number: $PR_NUMBER"
         echo "Preview dir: /var/www/preview/pr-${PR_NUMBER}"
@@ -28,15 +40,30 @@ jobs:
       shell: sh
       run: |
         set -eu
+        # 先检查是否已存在ssh
+        if command -v ssh >/dev/null 2>&1 && command -v ssh-keyscan >/dev/null 2>&1; then
+          echo "SSH client already available: $(ssh -V 2>&1)"
+          exit 0
+        fi
+        # 尝试多种包管理器安装
         if command -v apk >/dev/null 2>&1; then
           apk add --no-cache openssh-client >/dev/null 2>&1
+          echo "openssh-client installed via apk"
         elif command -v apt-get >/dev/null 2>&1; then
           apt-get update -qq && apt-get install -y -qq openssh-client >/dev/null 2>&1
+          echo "openssh-client installed via apt-get"
+        elif command -v yum >/dev/null 2>&1; then
+          yum install -y openssh-clients >/dev/null 2>&1
+          echo "openssh-client installed via yum"
+        elif command -v dnf >/dev/null 2>&1; then
+          dnf install -y openssh-clients >/dev/null 2>&1
+          echo "openssh-client installed via dnf"
         else
-          echo "ERROR: No package manager found"
+          echo "ERROR: No package manager found and ssh not pre-installed"
+          which ssh 2>/dev/null || echo "  ssh: not found"
+          which ssh-keyscan 2>/dev/null || echo "  ssh-keyscan: not found"
           exit 1
         fi
-        echo "openssh-client installed"
 
     - name: Remove preview directory from server
       shell: sh
@@ -101,7 +128,12 @@ jobs:
         GITHUB_TOKEN: ${{ github.token }}
       run: |
         set -eu
-        PR_NUMBER=$(echo "$GITHUB_REF" | sed 's|refs/pull/||; s|/.*||')
+        # 从event payload读取PR号（最可靠）
+        if [ -n "${GITHUB_EVENT_PATH:-}" ] && [ -f "$GITHUB_EVENT_PATH" ]; then
+          PR_NUMBER=$(python3 -c "import json,sys; print(json.load(sys.stdin).get('number',''))" < "$GITHUB_EVENT_PATH")
+        else
+          PR_NUMBER=$(echo "$GITHUB_REF" | sed -n 's|refs/pull/\([0-9]*\)/.*|\1|p')
+        fi
         export PR_NUMBER
 
         COMMENT_BODY=$(python3 scripts/ci/preview_comment.py cleanup)