docs: add release runbook

[cafitac]

Summary

• add a release runbook documenting version files, tag-triggered publish flow, workflow_dispatch fallback, and post-publish validation commands
• link the new runbook from the README release section
• verify the documented commands against the current published package and release guard

Testing

• uv run --extra dev python -m ai_crawler.release.npm_publish --event-name workflow_dispatch --ref-name main
• npm view @cafitac/ai-crawler version name dist-tags --json
• npm exec --yes @cafitac/ai-crawler@0.1.1 -- --version
• npm exec --yes @cafitac/ai-crawler@0.1.1 -- doctor
• npm exec --yes @cafitac/ai-crawler@0.1.1 -- mcp-config --client hermes --launcher npm
• npm install @cafitac/ai-crawler@0.1.1 && ./node_modules/.bin/ai-crawler --version && ./node_modules/.bin/ai-crawler doctor
• bash scripts/check-python.sh
• bash scripts/verify-ai-harness.sh