Add channels management to Sidebar and API index; update MaterialSubjects for icon handling

src/router/index.tsx

@@ -103,6 +103,7 @@ const Roles = lazy(() => import('@/pages/Roles'))
 const Posts = lazy(() => import('@/pages/Posts'))
 const Comments = lazy(() => import('@/pages/Comments'))
 const Groups = lazy(() => import('@/pages/Groups'))
+const Channels = lazy(() => import('@/pages/Channels'))
 const MaterialSubjects = lazy(() => import('@/pages/MaterialSubjects'))
 const Materials = lazy(() => import('@/pages/Materials'))
 const Forbidden = lazy(() => import('@/pages/Forbidden'))
@@ -193,6 +194,16 @@ export const router = createBrowserRouter([
           </ModeratorGuard>
         ),
       },
+      {
+        path: 'channels',
+        element: (
+          <AdminGuard>
+            <Suspense fallback={<PageLoader />}>
+              <Channels />
+            </Suspense>
+          </AdminGuard>
+        ),
+      },
       {
         path: 'materials/subjects',
         element: (