Remove + Новый header link and equalize nav weight

Drop the active-class on nav links so Лиды and Статистика render with
identical weight regardless of current route. Removes the + Новый shortcut
from the header (still accessible via the Добавить лида CTA on the list).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

leadscore/frontend/src/App.vue

@@ -39,25 +39,13 @@ function userInitials(name: string | undefined): string {
             <span class="font-semibold tracking-tight text-[15px]">Lead Scoring</span>
           </RouterLink>
           <nav class="flex items-center gap-5">
-            <RouterLink
-              :to="{ name: 'leads' }"
-              class="nav-link"
-              active-class="nav-link-active"
-            >
+            <RouterLink :to="{ name: 'leads' }" class="nav-link">
               Лиды
             </RouterLink>
-            <RouterLink
-              :to="{ name: 'new-lead' }"
-              class="nav-link"
-              active-class="nav-link-active"
-            >
-              + Новый
-            </RouterLink>
             <RouterLink
               v-if="auth.isRop"
               :to="{ name: 'stats' }"
               class="nav-link"
-              active-class="nav-link-active"
             >
               Статистика
             </RouterLink>