Agent Skills: create-pr

Creates GitHub pull requests with pre-flight validation, conventional title formatting, and structured summary generation. Runs parallel checks (tests, lint, type-check, security) before opening. Supports feature, bugfix, refactor, and hotfix PR types with milestone assignment via gh CLI. Invoke only if the operator named it; an everyday `gh pr create` stays plain tooling. Use when opening PRs or submitting code for review.