feat: add schedulers feature with task management

- Introduced SchedulersPage for managing scheduled tasks.
- Implemented CreateTaskDialog for creating new scheduled tasks.
- Added SchedulersHeader for filtering and searching tasks.
- Created SchedulersTable to display scheduled tasks with actions.
- Implemented loading and error states with SchedulersLoadingStates.
- Added API service for task management in schedulers.
- Enhanced date formatting utility to handle timezone.
- Updated AppSidebar and AppRoutes to include SchedulersPage.

src/components/AppSidebar.tsx

@@ -8,6 +8,7 @@ import {
 } from '@/components/ui/sidebar'
 import { useAuth } from '@/contexts/AuthContext'
 import {
+  CalendarClock,
   Download,
   Home,
   Music,
@@ -48,6 +49,7 @@ export function AppSidebar({ showCompactPlayer = false }: AppSidebarProps) {
           <NavItem href="/sounds" icon={Music} title="Sounds" />
           <NavItem href="/playlists" icon={PlayCircle} title="Playlists" />
           <NavItem href="/extractions" icon={Download} title="Extractions" />
+          <NavItem href="/schedulers" icon={CalendarClock} title="Schedulers" />
         </NavGroup>
 
         {user.role === 'admin' && (