ci: link Marketplace and GitHub releases

[realSilasYang]

修改内容

• 将版本标签工作流改为先发布 VS Code Marketplace，再创建或更新 GitHub Release。
• 使用同一个 VSIX，并在发布后下载 Marketplace 包进行 SHA-256 一致性校验。
• 支持重复运行、全局发布串行化和凭据缺失时失败封闭。
• 更新 README、发布指南和发布契约验证。

验证

• 已运行 npm run verify
• 涉及 VS Code 生命周期时，已运行 npm run test:integration（本次不修改扩展运行逻辑，PR CI 仍会运行集成测试）
• 已运行 npm audit --audit-level=high（本次不修改依赖，PR CI 仍会运行依赖审计）
• 用户可见变化已更新 README 和 CHANGELOG（已更新 README 与 RELEASING；无需修改 CHANGELOG）
• 未提交 API Key、书签数据、本机路径、构建产物或其他敏感信息
• GitHub Actions 专用校验器与 Prettier YAML 检查通过
• 已验证 v1.0.0 的 GitHub 与 Marketplace VSIX SHA-256 完全一致

兼容性与数据影响

不影响扩展运行、设置、持久化格式或书签数据。下一次推送 v* 标签前必须配置仓库 Secret VSCE_PAT。

[Copilot]

Pull request overview

This PR updates the tag-triggered release automation so a single built VSIX is first published to the VS Code Marketplace, then used to create/update the corresponding GitHub Release, with a post-publish SHA-256 consistency check to ensure the Marketplace package matches the built artifact.

Changes:

• Update release.yml to (1) validate Marketplace publishing config, (2) publish via vsce, (3) download the Marketplace VSIX and compare SHA-256, then (4) create or update the GitHub Release, with global release concurrency.
• Strengthen the “release readiness contract” script to assert the new workflow requirements and step ordering.
• Update release documentation (RELEASING + README) to describe the linked Marketplace + GitHub Release process and required secrets/variables.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
scripts/verify-release-readiness.js	Extends the release workflow contract verification to cover Marketplace publish + hash verification + ordering constraints.
.github/workflows/release.yml	Implements serialized, repeatable Marketplace publish + Marketplace artifact hash verification + GitHub Release create/update.
RELEASING.md	Updates the release runbook to match the new linked publication flow and required VSCE_PAT secret.
README.md	Updates the release checklist note to reflect the linked Marketplace + GitHub Release workflow.

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