Agent Skills: ring:pinning-dependency-versions

Pinning an explicit versioned dependency manifest (dependencies.md plus PROJECT_RULES.md): exact package versions, CVE and license checks, compatibility matrices, and per-component cost analysis against Ring Standards. Gate 6 of ring:planning-large-features; runs after ring:designing-data-model, before ring:writing-plans. Use when the schema is validated and you are about to lock products and versions. Skip for Small Track or when versions are already locked.