Add CI workflows for build, PR checks, and pre-release

[XChen446]

• 配置构建工作流，支持推送和标签触发，使用JDK 21构建并上传JAR制品
• 设置PR检查工作流，包含依赖缓存隔离和测试执行
• 创建预发布工作流，在构建成功后自动创建GitHub预发布版本
• 使用Maven缓存优化构建性能，配置30天制品保留策略
• 实现PR依赖缓存严格隔离，防止缓存污染和安全问题
• 添加测试报告上传功能，便于质量监控和问题排查

[TheCommandCraft]

Thanks for setting up CI! A few things need addressing before this can merge:

1. build.yml skips tests on every push including main. Tests should run on main, either change to mvn clean verify or add a separate job that runs tests on main pushes.

2. The test report upload path is target/surefire-reports/ but this is a multi-module project, the actual reports are under vanishpp-paper/target/surefire-reports/. Change to **/target/surefire-reports/.

3. Please translate the inline Chinese comments to English to stay consistent with the rest of the codebase.

4. Minor: all three files are missing a trailing newline.

[XChen446]

Thks for pointing out ,review it again plz

[TheCommandCraft]

Hey, thanks again for putting this together, PR checks, and tag-based pre-releases is something the project has needed for a while, and the overall structure you've set up is exactly right. Really appreciate the effort!

Just one last thing before this can merge: the prerelease.yml download step is still missing two required fields. When a workflow_run-triggered workflow tries to download artifacts, download-artifact@v4 defaults to the current run (the prerelease run), not the build run that produced the JARs. Without run-id it won't find anything and the release will fail on every tag push.

The fix is small:

- name: Download all artifacts from build workflow
  uses: actions/download-artifact@v4
  with:
    name: build-artifacts-${{ github.event.workflow_run.head_sha }}
    path: downloaded-artifacts
    run-id: ${{ github.event.workflow_run.id }}
    github-token: ${{ secrets.GITHUB_TOKEN }}

Once that's in, everything else looks good and this is ready to go!