Add automated pnpm-lock.yaml conflict resolution workflow

[Copilot]

Merge conflicts in pnpm-lock.yaml are a recurring friction point in monorepo workflows. This PR adds automation to detect and resolve lockfile-only conflicts automatically.

Implementation

• New workflow (.github/workflows/pnpm-lock-autofix.yml):

  • Triggers on PR events when lockfile or package.json changes
  • Detects merge conflicts via attempted base branch merge
  • If only pnpm-lock.yaml conflicts: regenerates via pnpm install --no-frozen-lockfile, commits, and pushes
  • If multiple files conflict: notifies with manual resolution steps
  • Fork-safe: only runs on same-repo PRs

• Documentation:

  • Added workflow explanation with flow diagram to .github/WORKFLOWS.md
  • Added troubleshooting section to CONTRIBUTING.md

Behavior

PR with lockfile conflict → Detect conflict → Only pnpm-lock.yaml?
                                                    ↓ yes          ↓ no
                                            Auto-regenerate    Notify user
                                                    ↓
                                            Commit & push
                                                    ↓
                                            Comment on PR

Security: Uses github.event.pull_request.head.repo.full_name == github.repository guard to prevent execution on fork PRs.

Original prompt

创建自动化流程，防止合并分支时报错 pnpm lock 冲突

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[github-actions]

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