fix: opacity fotos + audit completo + rollback legal pages

- Hero: Maldonado aerial opacity 0.12→0.30
- DifferenceCards: card photo opacity 0.06→0.15
- ProcessSteps: section photo opacity 0.05→0.15
- servicios/[slug] + en mirror: full Tailwind v3→CSS vars migration
- PricingTiers + PricingTiersFeatured: rounded-2xl→glass-card
- en/plans: hardcoded Spanish H1→i18n + reveal
- planes, servicios/index, en/servicios/index: reveal en hero
- legal pages: bg-hds-marfil+text-hds-humo→CSS vars

src/components/DifferenceCards.astro

@@ -33,7 +33,7 @@ const items = [
       {items.map((item, i) => (
         <article class="glass-card diff-card p-8 flex flex-col relative overflow-hidden" data-diff-index={i}>
           {item.photo && (
-            <div class="absolute inset-0 pointer-events-none" aria-hidden="true" style="opacity: 0.06;">
+            <div class="absolute inset-0 pointer-events-none" aria-hidden="true" style="opacity: 0.15;">
               <img
                 src={`${item.photo}.webp`}
                 alt=""