#425 Add release operator checklist

Summary

• add an ordered release operator checklist for xy and the bundled reflex_xy integration
• document version/tag safety, Rust-backed and coreless sdist validation, release monitoring, clean-install smoke tests, and recovery paths
• add a Remotion release-video and LinkedIn thumbnail brief with verified-content, visual, delivery, QA, and explicit approval requirements
• link the checklist from the contributor and production-readiness documentation

Why

The production-readiness spec captures release invariants, but maintainers also need an end-to-end operating procedure. This records the lessons from the 0.0.5 release, especially PyPI immutability, Rust/native verification, optional Reflex boundaries, testing the published package from a clean environment, and preparing accurate release media without publishing before approval.

Impact

Documentation only. Release maintainers get a repeatable release and media-production path without changes to package or workflow behavior.

Validation

• uv run --with pre-commit pre-commit run --all-files
• uv run ruff check .
• uv run ruff format --check .
• .venv/bin/python scripts/verify_local.py --only examples — 9 passed, 2 skipped
• git diff --cached --check

Summary by CodeRabbit

• Documentation
  • Added an ordered release checklist covering preparation, dry-run builds, changelog updates, approval, publishing, verification, and sign-off.
  • Documented checks for package immutability, clean installs, published examples, and release deliverables.
  • Added recovery guidance for release failures and retries, including preserving accepted package files while uploading missing ones.
  • Updated contribution and production-readiness guidance to reference the checklist.