refactor: 优化发布流程 - PR 合并时触发，自动清理旧版本

主要改进：
- 改为 PR 合并到 main 时触发（不是每次 push）
- 自动删除超过 10 个的旧 Release，保持发布历史整洁
- 移除 prerelease 标记，所有自动构建都是正式 Release
- 恢复使用 v 前缀的版本号格式
- 清理了现有的 Draft 状态 Release

工作流程：
1. PR 合并到 main 分支时自动构建并发布
2. 自动清理，只保留最近 10 个 Release
3. 手动触发 tag-release.yml 发布语义化版本

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.github/workflows/release.yml

@@ -1,12 +1,9 @@
 name: Build and Release
 
 on:
-  push:
+  pull_request:
+    types: [closed]
     branches: [ main ]
-    paths:
-      - '**.go'
-      - 'go.mod'
-      - 'go.sum'
   workflow_dispatch:
 
 permissions:
@@ -15,6 +12,8 @@ permissions:
 jobs:
   build:
     runs-on: ubuntu-latest
+    # 只在 PR 被合并时运行，或手动触发
+    if: (github.event.pull_request.merged == true) || (github.event_name == 'workflow_dispatch')
 
     steps:
     - uses: actions/checkout@v4
@@ -31,9 +30,9 @@ jobs:
       run: |
         TIMESTAMP=$(date +%Y.%m.%d.%H%M)
         COMMIT_SHA=$(git rev-parse --short HEAD)
-        RELEASE_NAME="Build-${TIMESTAMP}-${COMMIT_SHA}"
-        echo "release_name=${RELEASE_NAME}" >> $GITHUB_OUTPUT
-        echo "Generated release: ${RELEASE_NAME}"
+        VERSION="v${TIMESTAMP}-${COMMIT_SHA}"
+        echo "version=${VERSION}" >> $GITHUB_OUTPUT
+        echo "Generated version: ${VERSION}"
 
     - name: Build for multiple platforms
       run: |
@@ -54,13 +53,27 @@ jobs:
         GOOS=linux GOARCH=amd64 go build -o xiaohongshu-mcp-linux-amd64 .
         GOOS=linux GOARCH=amd64 go build -o xiaohongshu-login-linux-amd64 ./cmd/login
 
-    - name: Create Release (without permanent tag)
+    - name: Clean up old releases
+      run: |
+        # 获取所有自动构建的 releases (v开头的时间戳格式)
+        RELEASES=$(gh release list --limit 100 | grep -E '^v[0-9]{4}\.[0-9]{2}\.[0-9]{2}\.[0-9]{4}-' | awk '{print $3}' | tail -n +11)
+
+        # 删除超过 10 个的旧 releases 和对应的 tags
+        for release in $RELEASES; do
+          echo "Deleting old release: $release"
+          gh release delete "$release" --yes --cleanup-tag
+        done
+      env:
+        GH_TOKEN: ${{ github.token }}
+      continue-on-error: true
+
+    - name: Create Release
       uses: softprops/action-gh-release@v1
       with:
-        tag_name: ${{ steps.version.outputs.release_name }}
-        name: ${{ steps.version.outputs.release_name }}
+        tag_name: ${{ steps.version.outputs.version }}
+        name: Release ${{ steps.version.outputs.version }}
         draft: false
-        prerelease: true
+        prerelease: false
         body: |
           ## 🔧 自动构建版本
 
@@ -94,7 +107,7 @@ jobs:
 
           - **Commit**: ${{ github.sha }}
           - **Branch**: main
-          - **Build Time**: ${{ steps.version.outputs.release_name }}
+          - **Build Time**: ${{ steps.version.outputs.version }}
         files: |
           xiaohongshu-mcp-darwin-arm64
           xiaohongshu-mcp-darwin-amd64