v4.2.2 — Skill frontmatter YAML fix + n8nac >= 2.2 .env handling

Two bugs found via claude --debug log inspection in a consumer repo.

1. YAML parse failure in 2 skill frontmatters — n8nac-cheatsheet and build-workflow had unquoted description: values containing <word>: <word> (e.g. "common workflows: lookup"), which js-yaml interprets as a nested mapping. Both skills were silently dropped from every session. Cheatsheet was the worst hit — entire curated CLI-mapping was invisible to consumers despite shipping in v4.2.0. Fixed by quoting the descriptions and replacing inline colons with em-dashes.

2. check-installed-nodes warned about missing .env on bound workspaces — n8nac >= 2.2 stores the API key in the secure manager store (~/.n8n-manager/), not in a workspace .env. The schema-coverage probe needs that key to query /community-packages but cannot retrieve it from the secure store. Pre-4.2.2 just printed a misleading "ℹ️ .env not found — skipping" on every session. Now silent-skips with an explanatory note when the workspace is bound, keeps the warning only when truly unconfigured.

Full changelog: https://github.com/neurawork-git/n8n-autopilot/blob/main/CHANGELOG.md#422--2026-05-20