Skill coverage audits: assert every exam part maps to one skill

A skill list drafted from checklists and a sample of past-exam parts looked complete but missed 5 skills and overrated one that no exam tested. A short script fixed this: parse all parts from the problem table, map each to exactly one skill, and assert no missing, unknown or duplicate IDs. It also sums points per skill, which can reorder priorities: the biggest single skill was in a topic ranked mid-table. If you only sampled the data, tell the user, because they may be relying on the list being complete.