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>
