Implement BumperEndpoints and remove deprecated bumper-related functionality

Added new BumperEndpoints to the API for managing bumper templates and variants, enhancing the channel management capabilities. Removed outdated bumper-related commands and handlers from the application, streamlining the codebase and improving maintainability. Updated ChannelEndpoints to reflect these changes and ensure proper routing for the new endpoints.

frontend/src/routes/admin.tsx

@@ -64,6 +64,20 @@ function AdminLayout() {
         >
           {t('admin.channels.title')}
         </Link>
+        <Link
+          to="/admin/junctions"
+          className={cn('pb-2 uppercase tracking-wide text-muted-foreground hover:text-foreground')}
+          activeProps={{ className: 'border-b-2 border-primary text-primary' }}
+        >
+          {t('admin.junctions.title')}
+        </Link>
+        <Link
+          to="/admin/bumpers"
+          className={cn('pb-2 uppercase tracking-wide text-muted-foreground hover:text-foreground')}
+          activeProps={{ className: 'border-b-2 border-primary text-primary' }}
+        >
+          {t('admin.bumpers.title')}
+        </Link>
         <Link
           to="/admin/gallery"
           className={cn('pb-2 uppercase tracking-wide text-muted-foreground hover:text-foreground')}

frontend/src/routes/admin/bumpers.tsx

@@ -0,0 +1,4 @@
+import { createFileRoute } from '@tanstack/react-router'
+import { BumpersPanel } from '@/features/admin/bumpers/BumpersPanel'
+
+export const Route = createFileRoute('/admin/bumpers')({ component: BumpersPanel })

frontend/src/routes/admin/junctions.tsx

@@ -0,0 +1,4 @@
+import { createFileRoute } from '@tanstack/react-router'
+import { JunctionsPanel } from '@/features/admin/junctions/JunctionsPanel'
+
+export const Route = createFileRoute('/admin/junctions')({ component: JunctionsPanel })