helix-skill-400-line-hard-limit-now-lint-enforced

Helix skills must not exceed 400 lines — this is the progressive-disclosure hard limit preventing skills from becoming reference manuals. The limit is now enforced by fusion-invariants-lint.py. Two violations were found and refactored this session: website-creator (583→282 lines, 3 new references/ docs) and frontend-redesign (410→128 lines, new docs/ subdir). Skill body should contain triggers + contracts; detailed procedures move to references/ subdocs.