Agent Skills: paid-tier-readiness-check

Evaluates whether substacker has the four preconditions for launching a paid tier — enough subs, healthy engagement, a clear candidate section, writer capacity. Produces readiness score (not-ready / close / ready) with named gaps. Used when the "should we launch paid?" question is selected or at writer's explicit request. Trigger keywords — paid tier, paid readiness, monetization, Substack paid, launch paid, 1000 subscribers.