Release 0.5.7 and require PR release metadata

[crankshift]

Summary

• Bump package, CLI, and plugin metadata versions to 0.5.7.
• Add the 0.5.7 changelog entry for the forwarded Telegram author context fix from [Task]: Add forwarded message author context to Telegram prompts #19.
• Require future PRs to update package.json and CHANGELOG.md so merges trigger a new release tag build.

Closes #22.

Test Plan

• pnpm vitest run tests/runtime/aiSkillRegistration.test.js
• pnpm run lint
• pnpm test
• pnpm run check