feat: 添加自动版本发布功能

- 新增 auto-release.yml 工作流，推送到 main 分支时自动递增版本号
- 自动创建 GitHub Release 和生成更新日志
- 添加 AUTO_RELEASE_GUIDE.md 详细使用指南
- 更新 WORKFLOW_USAGE.md 说明文档

现在每次推送到 main 分支都会自动：
1. 递增 patch 版本号（如 v1.0.1 → v1.0.2）
2. 创建新的 Git 标签和 GitHub Release
3. 生成更新日志并更新 CHANGELOG.md

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

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

.github/workflows/auto-release.yml

@@ -0,0 +1,132 @@
+name: Auto Release on Push to Main
+
+on:
+  push:
+    branches:
+      - main
+    paths-ignore:
+      - '**.md'
+      - '.github/**'
+      - 'docs/**'
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  auto-release:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+        token: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Get latest tag
+      id: get_latest_tag
+      run: |
+        # 获取最新的版本标签
+        LATEST_TAG=$(git describe --tags --abbrev=0 2>/dev/null || echo "v0.0.0")
+        echo "Latest tag: $LATEST_TAG"
+        echo "latest_tag=$LATEST_TAG" >> $GITHUB_OUTPUT
+        
+        # 提取版本号部分（去掉 v 前缀）
+        VERSION=${LATEST_TAG#v}
+        echo "version=$VERSION" >> $GITHUB_OUTPUT
+
+    - name: Calculate next version
+      id: next_version
+      run: |
+        VERSION="${{ steps.get_latest_tag.outputs.version }}"
+        
+        # 分割版本号为 major.minor.patch
+        IFS='.' read -r -a version_parts <<< "$VERSION"
+        MAJOR="${version_parts[0]:-0}"
+        MINOR="${version_parts[1]:-0}"
+        PATCH="${version_parts[2]:-0}"
+        
+        # 递增 patch 版本号
+        NEW_PATCH=$((PATCH + 1))
+        NEW_VERSION="${MAJOR}.${MINOR}.${NEW_PATCH}"
+        NEW_TAG="v${NEW_VERSION}"
+        
+        echo "New version: $NEW_VERSION"
+        echo "New tag: $NEW_TAG"
+        echo "new_version=$NEW_VERSION" >> $GITHUB_OUTPUT
+        echo "new_tag=$NEW_TAG" >> $GITHUB_OUTPUT
+
+    - name: Generate changelog
+      id: changelog
+      uses: orhun/git-cliff-action@v3
+      with:
+        config: .github/cliff.toml
+        args: --unreleased --strip header
+
+    - name: Check if there are changes to release
+      id: check_changes
+      run: |
+        # 检查自上次标签以来是否有新的提交
+        LATEST_TAG="${{ steps.get_latest_tag.outputs.latest_tag }}"
+        if [ "$LATEST_TAG" = "v0.0.0" ]; then
+          echo "has_changes=true" >> $GITHUB_OUTPUT
+        else
+          CHANGES=$(git rev-list $LATEST_TAG..HEAD --count)
+          if [ "$CHANGES" -gt 0 ]; then
+            echo "has_changes=true" >> $GITHUB_OUTPUT
+          else
+            echo "has_changes=false" >> $GITHUB_OUTPUT
+          fi
+        fi
+
+    - name: Create and push tag
+      if: steps.check_changes.outputs.has_changes == 'true'
+      run: |
+        NEW_TAG="${{ steps.next_version.outputs.new_tag }}"
+        git config user.name "github-actions[bot]"
+        git config user.email "github-actions[bot]@users.noreply.github.com"
+        git tag -a "$NEW_TAG" -m "Release $NEW_TAG"
+        git push origin "$NEW_TAG"
+
+    - name: Create Release
+      if: steps.check_changes.outputs.has_changes == 'true'
+      uses: softprops/action-gh-release@v1
+      with:
+        tag_name: ${{ steps.next_version.outputs.new_tag }}
+        name: Release ${{ steps.next_version.outputs.new_version }}
+        body: |
+          ## 🐳 Docker 镜像
+          
+          ```bash
+          docker pull ${{ secrets.DOCKERHUB_USERNAME || 'weishaw' }}/claude-relay-service:${{ steps.next_version.outputs.new_tag }}
+          docker pull ${{ secrets.DOCKERHUB_USERNAME || 'weishaw' }}/claude-relay-service:latest
+          ```
+          
+          ## 📦 主要更新
+          
+          ${{ steps.changelog.outputs.content }}
+          
+          ## 📋 完整更新日志
+          
+          查看 [CHANGELOG.md](https://github.com/${{ github.repository }}/blob/main/CHANGELOG.md)
+          
+          ---
+          *此版本由 GitHub Actions 自动发布*
+        draft: false
+        prerelease: false
+        generate_release_notes: true
+
+    - name: Update CHANGELOG.md
+      if: steps.check_changes.outputs.has_changes == 'true'
+      run: |
+        # 生成完整的 CHANGELOG
+        git cliff --config .github/cliff.toml --output CHANGELOG.md
+        
+        # 提交 CHANGELOG 更新
+        if git diff --quiet CHANGELOG.md; then
+          echo "No changes to CHANGELOG.md"
+        else
+          git add CHANGELOG.md
+          git commit -m "chore: update CHANGELOG.md for ${{ steps.next_version.outputs.new_tag }} [skip ci]"
+          git push origin main
+        fi