Peer linters

markdownlint-cli2, Vale, Prettier, markdown-link-check are not bundled.

Detection order: node_modules/.bin → PATH → skip with info. merlon check skips a missing markdown-link-check without the info line.

Use --require-lint / --require-vale in CI.

Separation of concerns: markdownlint covers Markdown structure, and Vale styles cover prose. Core stays on structural validation, the Check gate stages that don’t run a peer. Preferred homes says which tool checks each rule. @merlon-docs/merlon-docs-presets holds the starter markdownlint configs and the MerlonDocs Vale style, and a host can add other styles such as Microsoft.

Part of Design constraints.