[Feature] add CI workflow for TS SDK unit tests

**Feature Category**
- [ ] Sandbox
- [ ] Actions
- [ ] Deployments
- [ ] SDK & API
- [ ] Envhub
- [ ] CLI
- [x] Performance & Optimization
- [ ] Documentation & Examples

**Problem Statement**

**Proposed Solution**
新建 CI 工作流 ts-sdk-ci.yml，自动运行 TS SDK 的单元测试。
**Detailed Feature Description**

1. 工作流结构（单 Job / 6 Steps）
- Checkout 代码
- 安装 Node.js 20
- 安装 pnpm 并通过 pnpm install --frozen-lockfile 安装依赖
- 运行单元测试（pnpm test:unit，即 jest --selectProjects unit，测试 src/ 下的 *.test.ts）过后执行）
2. 触发条件
- push / pull_request 到 master 或 release/*
- workflow_dispatch 手动触发
3. 涉及文件
- 新增：.github/workflows/ts-sdk-ci.yml

Create .github/workflows/ts-sdk-ci.yml following the six listed steps: checkout, set up Node.js 20, install pnpm and dependencies with the frozen lockfile, and run pnpm test:unit. Verify that push and pull_request events for master and release/* plus workflow_dispatch trigger the job, and that the unit tests pass.

Written by the indexing model from the issue text.