feat: floating contact bar, remove pricing contact links, fix admin hooks

- Add FloatingContact bar (Записаться + Instagram) visible while scrolling
- Hides on hero and near contact section, centered at bottom
- Move BackToTop button up to avoid overlap
- Remove redundant ContactHint from Pricing section (floating bar covers it)
- Fix React hooks order violation in AdminLayout (early return before useEffect)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app/page.tsx

@@ -9,6 +9,7 @@ import { News } from "@/components/sections/News";
 import { FAQ } from "@/components/sections/FAQ";
 import { Contact } from "@/components/sections/Contact";
 import { BackToTop } from "@/components/ui/BackToTop";
+import { FloatingContact } from "@/components/ui/FloatingContact";
 import { Header } from "@/components/layout/Header";
 import { Footer } from "@/components/layout/Footer";
 import { getContent } from "@/lib/content";
@@ -42,6 +43,7 @@ export default function HomePage() {
         <FAQ data={content.faq} />
         <Contact data={content.contact} />
         <BackToTop />
+        <FloatingContact />
       </main>
       <Footer />
     </>