Adds docs/history/fase-12-section-visibility.md describing the COALESCE-precedence design that keeps Fase 13's server-settings layer to a one-line diff, the realtime publication addition that SV-02 forced, and the hermetic test-reset deviation from the plan. Updates CLAUDE.md project status (2/6 → 4/6 since Fase 11 and 12 both shipped on the mvp2 branch) and adds the "new top-level section requires" rule under Domain Model. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>