Harness Skill Creator

Scaffold a governed skill (6/6 by construction). The "Create" step of the harness journey — generates a new skill already wired to all 6 conventions (config, on-disk audit, observability, evidence-bearing arbiter, dry-run, disk scoreboard) via the harness-runtime sibling, so it scores 6/6 on harness-lint with zero manual retrofit.

by @ericsantos