Implemented `insomnia memory lint` as a headless command in the existing user-facing `insomnia` binary. The command lints workspace memory/knowledge records with the existing `memory::Linter` using `WriteMode::Update`, supports human and JSON output, handles warnings-as-errors, preserves `insomnia memory` as a positional Pod name, and returns before TUI/raw-terminal or Pod connection paths. External review approved and validation passed.
