validate-pr（验证公关）

Validate the current Pull Request against Marshroom conventions.

Steps:

1. Read ${MARSHROOM_STATE:-~/.config/marshroom/state.json} and parse the JSON
2. Run git branch --show-current to get the current branch name
3. Find the cart entry whose branchName matches the current git branch. If no match, tell the user they're not on a cart issue branch
4. Get the current PR info: gh pr view --json title,body,headRefName
5. Validate the following:

Branch Name Check:

• The PR's head branch should match the matched cart entry's branchName
• Expected format: Feature/#N or HotFix/#N
• If mismatched, show: "Branch mismatch: expected '{branchName}', got '{actual}'"

PR Body Check:

• The body MUST contain close #{issueNumber}
• If missing, suggest: gh pr edit --body "$(gh pr view --json body -q '.body')\n\nclose #<issueNumber>"

Status Check:

• Read the status field from the matched cart entry
• After PR creation, status should be "pending"
• If status is still "running", warn that the status was not updated (suggest running marsh pr)
• If status is "soon", warn that /start-issue may not have been run

Summary:

• Show pass/fail status for each check
• If all checks pass, confirm the PR is valid
• If any check fails, provide the fix commands