refactor: centralize gold tokens, extract sub-components, clean up unused code

- Replace hardcoded hex colors with gold/gold-light/gold-dark Tailwind tokens
- Extract Schedule into DayCard, ScheduleFilters, MobileSchedule sub-components
- Extract Team into TeamCarousel, TeamMemberInfo sub-components
- Add UI_CONFIG for centralized magic numbers (timings, thresholds)
- Add reusable IconBadge component, simplify Contact section
- Convert Pricing clickable divs to semantic buttons for a11y
- Remove unused SocialLinks, btn-outline, btn-ghost, nav-link CSS classes
- Fix React setState-during-render error in TeamCarousel (deferred update pattern)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/ui/BackToTop.tsx

@@ -2,13 +2,14 @@
 
 import { useState, useEffect } from "react";
 import { ChevronUp } from "lucide-react";
+import { UI_CONFIG } from "@/lib/config";
 
 export function BackToTop() {
   const [visible, setVisible] = useState(false);
 
   useEffect(() => {
     function handleScroll() {
-      setVisible(window.scrollY > 600);
+      setVisible(window.scrollY > UI_CONFIG.scrollThresholds.backToTop);
     }
     window.addEventListener("scroll", handleScroll, { passive: true });
     return () => window.removeEventListener("scroll", handleScroll);
@@ -18,7 +19,7 @@ export function BackToTop() {
     <button
       onClick={() => window.scrollTo({ top: 0, behavior: "smooth" })}
       aria-label="Наверх"
-      className={`fixed bottom-6 right-6 z-40 flex h-10 w-10 items-center justify-center rounded-full border border-[#c9a96e]/30 bg-black/60 text-[#d4b87a] backdrop-blur-sm transition-all duration-300 hover:bg-[#c9a96e]/20 hover:border-[#c9a96e]/50 ${
+      className={`fixed bottom-6 right-6 z-40 flex h-10 w-10 items-center justify-center rounded-full border border-gold/30 bg-black/60 text-gold-light backdrop-blur-sm transition-all duration-300 hover:bg-gold/20 hover:border-gold/50 ${
         visible ? "translate-y-0 opacity-100" : "translate-y-4 opacity-0 pointer-events-none"
       }`}
     >