refactor: перевёл цвета на CSS-переменные

frontend/src/components/layout/AppSidebar.vue

@@ -66,7 +66,7 @@ function isActive(to: string) {
   left: 0;
   bottom: 0;
   width: var(--sidebar-width);
-  background: rgba(255,255,255,0.75);
+  background: var(--color-white-glass);
   backdrop-filter: blur(16px);
   -webkit-backdrop-filter: blur(16px);
   border-right: 1px solid var(--color-border-glass);
@@ -96,14 +96,14 @@ function isActive(to: string) {
   transition: all 0.2s;
 }
 .nav-item:hover {
-  background: rgba(34,197,94,0.1);
+  background: var(--color-primary-a10);
   color: var(--color-primary-dark);
 }
 .nav-item.active {
-  background: linear-gradient(135deg, rgba(34,197,94,0.18), rgba(134,239,172,0.12));
+  background: var(--gradient-nav-active);
   color: var(--color-primary-dark);
   font-weight: 700;
-  box-shadow: 0 2px 8px rgba(34,197,94,0.12);
+  box-shadow: 0 2px 8px var(--color-primary-a12);
 }
 .nav-icon { flex-shrink: 0; color: currentColor; }
 .sidebar-footer {