feat: comprehensive light theme support across entire site

- CSS foundation: theme-aware scrollbars, section glows, glass cards with
  gold shadows, stronger animated borders and glow effects for light mode
- Hero: consistent dark-video treatment for both themes, brighter gold
  gradient text, glowing CTA button
- Gradient text: auto-switch to warm gold tones on light backgrounds via
  html:not(.dark) selector
- Team profile: inverted ambient photo bg with white overlay for light,
  dark text/borders, gold-dark labels for contrast
- All sections: text-neutral-500→600 upgrades for WCAG AA contrast,
  gold shadow accents on cards (About, Pricing, FAQ, DayCard, News)
- Admin: replaced hardcoded #c9a96e with theme tokens, fixed select
  options, array editor borders, booking badges contrast
- Header: white text on transparent hero, dark text after scroll
- UI components: BackToTop, FloatingHearts, ShowcaseLayout tabs,
  SignupModal, NewsModal, GroupCard adapted for light backgrounds
- Updated CLAUDE.md to reflect dual theme support

src/components/sections/MasterClasses.tsx

@@ -136,7 +136,7 @@ function MasterClassDetail({
         role="dialog"
         aria-modal="true"
         aria-label={item.title}
-        className="relative w-full max-w-lg max-h-[90vh] overflow-y-auto rounded-2xl border border-white/10 bg-neutral-950 shadow-2xl"
+        className="relative w-full max-w-lg max-h-[90vh] overflow-y-auto rounded-2xl border border-neutral-200 bg-white dark:border-white/10 dark:bg-neutral-950 shadow-2xl"
         onClick={(e) => e.stopPropagation()}
       >
         {/* Content */}
@@ -147,7 +147,7 @@ function MasterClassDetail({
               {item.style}
             </span>
             {duration && (
-              <span className="flex items-center gap-1 text-xs text-white/50">
+              <span className="flex items-center gap-1 text-xs text-neutral-500 dark:text-white/50">
                 <Clock size={11} />
                 {duration}
               </span>
@@ -161,19 +161,19 @@ function MasterClassDetail({
             <button
               onClick={onClose}
               aria-label="Закрыть"
-              className="h-11 w-11 flex items-center justify-center rounded-full text-white/50 hover:text-white hover:bg-white/10 transition-colors shrink-0 -mr-2"
+              className="h-11 w-11 flex items-center justify-center rounded-full text-neutral-400 hover:text-neutral-900 hover:bg-neutral-100 dark:text-white/50 dark:hover:text-white dark:hover:bg-white/10 transition-colors shrink-0 -mr-2"
             >
               <X size={18} />
             </button>
           </div>
 
           {/* Title */}
-          <h2 className="text-2xl font-bold text-white">{item.title}</h2>
+          <h2 className="text-2xl font-bold text-neutral-900 dark:text-white">{item.title}</h2>
 
           {/* Trainer */}
           <button
             onClick={() => window.dispatchEvent(new CustomEvent("openTrainerProfile", { detail: item.trainer.split(" · ")[0] }))}
-            className="flex items-center gap-2 text-sm text-white/80 hover:text-gold transition-colors"
+            className="flex items-center gap-2 text-sm text-neutral-700 hover:text-gold dark:text-white/80 transition-colors"
           >
             <User size={14} />
             {item.trainer}
@@ -181,14 +181,14 @@ function MasterClassDetail({
 
           {/* Description */}
           {item.description && (
-            <div className="text-sm leading-relaxed text-white/60">
+            <div className="text-sm leading-relaxed text-neutral-600 dark:text-white/60">
               {formatMarkup(item.description)}
             </div>
           )}
 
           {/* All dates */}
           <div className="space-y-2">
-            <h3 className="text-sm font-medium text-white/40 uppercase tracking-wider">Даты</h3>
+            <h3 className="text-sm font-medium text-neutral-400 dark:text-white/40 uppercase tracking-wider">Даты</h3>
             {slots.length === 0 ? (
               <p className="text-sm text-gold">Скоро — дата уточняется</p>
             ) : (
@@ -198,11 +198,11 @@ function MasterClassDetail({
                   return (
                     <div key={i} className="flex items-center gap-3 text-sm">
                       <Calendar size={13} className="shrink-0 text-gold/60" />
-                      <span className="text-white/80">
+                      <span className="text-neutral-700 dark:text-white/80">
                         {d.getDate()} {MONTHS_RU[d.getMonth()]} ({WEEKDAYS_RU[d.getDay()]})
                       </span>
                       {slot.startTime && (
-                        <span className="text-white/50">
+                        <span className="text-neutral-500 dark:text-white/50">
                           {slot.startTime}–{slot.endTime}
                         </span>
                       )}
@@ -215,7 +215,7 @@ function MasterClassDetail({
 
           {/* Location */}
           {item.location && (
-            <div className="flex items-center gap-2 text-sm text-white/60">
+            <div className="flex items-center gap-2 text-sm text-neutral-500 dark:text-white/60">
               <MapPin size={13} className="text-gold/60" />
               <span>{item.location}{locAddress ? ` · ${locAddress}` : ""}</span>
             </div>
@@ -227,7 +227,7 @@ function MasterClassDetail({
               href={item.instagramUrl}
               target="_blank"
               rel="noopener noreferrer"
-              className="inline-flex items-center gap-2 text-sm text-white/50 hover:text-gold transition-colors"
+              className="inline-flex items-center gap-2 text-sm text-neutral-400 hover:text-gold dark:text-white/50 transition-colors"
             >
               <Instagram size={14} />
               Подробнее в Instagram