Site polish: tighter modalidades spacing, less schedule redundancy, plan section styling

- Modalidades: reduce gap between cards
- Horário: drop the day-title above the grid in single-day mode (the active
  day-filter button already names it); restyle "Guardar horário" as a plain
  link and drop the "(JPG)" suffix
- Mensalidades: give "Escolhe o teu plano" the same dark hammered-metal
  background as the reviews/footer sections instead of the plain light one

site/assets/js/main.js

@@ -200,7 +200,7 @@ document.addEventListener('DOMContentLoaded', function () {
     // ── Arrow buttons ─────────────────────────────────────────────────────
     function step(dir) {
         var card = scroller.querySelector('.mod-card');
-        var by = card ? (card.offsetWidth + 16) * Math.max(1, Math.floor(scroller.clientWidth / (card.offsetWidth + 16)) - 1) : 400;
+        var by = card ? (card.offsetWidth + 8) * Math.max(1, Math.floor(scroller.clientWidth / (card.offsetWidth + 8)) - 1) : 400;
         touched();
         if (dir < 0 && scroller.scrollLeft - by < 0) { scroller.scrollLeft += loopWidth(); }
         scroller.scrollBy({ left: dir * by, behavior: reduced.matches ? 'auto' : 'smooth' });