Landing: visible navbar with page links, remove price from dashboard

- Nav background visible immediately (semi-transparent dark with blur)
- Added Инструменты and Возможности links in nav (hidden on mobile)
- Added id=features to advantages section for smooth scroll
- Replaced 0₽ with Free label on dashboard about section

public/index.html

@@ -174,8 +174,8 @@
                 <div class="label">категории</div>
             </div>
             <div class="about-stat">
-                <div class="num">0 &#8381;</div>
+                <div class="num" style="color:#22c55e;">Free</div>
-                <div class="label">навсегда</div>
+                <div class="label">бесплатно</div>
             </div>
         </div>
     </div>