chore: 移除 GitHub Actions CI/CD（已迁移至内部 GitLab）

[yujiawei]

变更

移除 GitHub Actions 的 CI/CD workflows，构建和发布已迁移至国内 GitLab。

删除的文件：

• .github/workflows/ci.yml — Build & Test + @dev 自动发布
• .github/workflows/release.yml — @latest 正式发布 + Git tag

⚠️ 注意：此 PR 删除了 Build & Test workflow，因此该 required status check 不会通过。需要 admin merge 或先移除分支保护规则中的 status check 要求。

[Jerry-Xin]

The migration direction makes sense — if GitLab is now the canonical CI, keeping stale GitHub Actions workflows around is just confusing. A few things worth addressing before merging:

1. Conflicting with PR #152

PR #152 modifies release.yml to add contents: write permission, but this PR deletes release.yml entirely. These two PRs conflict — merging one invalidates the other. Should #152 be closed since the release workflow is moving to GitLab?

2. CONTRIBUTING.md still references GitHub CI

.github/CONTRIBUTING.md line 57 says:

确保 CI 检查全部通过

After this PR, there will be no GitHub CI checks to pass. This should be updated to reference the new GitLab CI, or at least generalized (e.g., "确保 CI 检查全部通过（见 GitLab pipeline）") so contributors know where to look.

3. PR #126 adds a new GitHub Actions workflow

PR #126 is open and proposes adding a new GitHub Actions workflow (pr-review.yml). If the intent is to move CI/CD off GitHub Actions entirely, that PR would re-introduce a workflow right after this one removes them. Worth coordinating — should the PR review automation also live in GitLab, or is GitHub Actions still the home for non-CI automation (like PR triage)?

4. Dependabot PRs will lose CI checks

dependabot.yml is still configured to open dependency update PRs on GitHub. With ci.yml removed, those PRs will have no automated checks on GitHub. Either:

• Move dependabot-equivalent scanning to GitLab (e.g., Renovate), or
• Keep a minimal CI workflow on GitHub just for PR validation, or
• Accept that dependabot PRs will need manual validation

5. Branch protection (acknowledged)

You've already flagged this in the PR description — the Build & Test required status check will need to be removed from branch protection rules before or alongside this merge. Just confirming this is tracked. 👍

Overall

The deletion itself is clean — just two file removals, no stale references in the workflow files themselves. The main gap is the surrounding ecosystem (docs, branch protection, dependabot, conflicting PRs) that still assumes GitHub CI exists.