V3 Markdown lint capability pack. By-value connector composition (service_kind=cli, no separate ingredient): one local markdownlint CLI ingredient exposes bounded project operations for readiness and Markdown lint diagnostics. Lints run from an explicit project directory cwd supplied at execution time, check one trusted Markdown file, directory, or glob, and return JSON findings via the markdown.lint catalog operation. Fixed-function and reproducible at the invocation boundary: JSON output, no fix mode, no output-file write, no stdin, no caller-supplied config path, no custom rules, no caller-supplied ignore path, no arbitrary markdownlint flags, no shell wrapper, and no network egress. The command disables MD013 line-length noise to make the pack useful for prose-heavy docs by default; remaining findings are represented as successful JSON output. Requires markdownlint on PATH. Local and no-egress.