dead-progressive-disclosure-refs-accumulate-silently

After the progressive-disclosure split (SKILL.md content moved to docs/references/), 189 prose pointers (Future: lines + bullet refs) across 65 skills pointed to non-existent deeper docs. These create false promises and violate Law 10 (dormant = removed). The fusion-invariants-lint was extended to detect prose-pointer deadness going forward; existing cleanup required a targeted script to strip all instances.