create-pr

When creating a PR:

• Use gh pr create
• Use the target repo's dedicated PR template when one exists.
• Otherwise, use pull_request_template.md from this package as the fallback template.
• Follow merge-queue conventions.

Merge-queue mapping

• PR title = commit title (Conventional Commits format).
• PR description = commit body (reusable as commit message content).
• PR title max: 72 characters.
• PR description line max: 72 characters, except long URLs, code blocks, or stack traces.

Description rules

• The first line must be plain context text describing the change.