refactor(frontend): Remove '/api' prefix from all API calls to align with backend URL convention

- Updated all API endpoint strings in 'frontend/src' (via sed and manual fixes) to remove the '/api/' prefix.
- Manually fixed 'Timeline.tsx' absolute URLs to use the 'api' subdomain and correct path.
- Manually fixed 'useAuth.ts' logout fetch URLs.
- Updated 'HelpApiDocs.tsx' sandbox URL.
- This change, combined with the backend URL update, fully transitions the application to use subdomain-based routing (e.g., 'http://api.lvh.me:8000/resource/') instead of path-prefix routing (e.g., 'http://api.lvh.me:8000/api/resource/').

frontend/src/components/CreateTaskModal.tsx

@@ -123,7 +123,7 @@ const CreateTaskModal: React.FC<CreateTaskModalProps> = ({ isOpen, onClose, onSu
   const { data: plugins = [], isLoading: pluginsLoading } = useQuery<PluginInstallation[]>({
     queryKey: ['plugin-installations'],
     queryFn: async () => {
-      const { data } = await axios.get('/api/plugin-installations/');
+      const { data } = await axios.get('/plugin-installations/');
       // Filter out plugins that already have scheduled tasks
       return data.filter((p: PluginInstallation) => !p.scheduled_task);
     },
@@ -209,7 +209,7 @@ const CreateTaskModal: React.FC<CreateTaskModalProps> = ({ isOpen, onClose, onSu
           apply_to_existing: applyToExisting,
         };
 
-        await axios.post('/api/global-event-plugins/', payload);
+        await axios.post('/global-event-plugins/', payload);
         queryClient.invalidateQueries({ queryKey: ['global-event-plugins'] });
         toast.success(applyToExisting ? 'Plugin attached to all events' : 'Plugin will apply to future events');
       } else {
@@ -240,7 +240,7 @@ const CreateTaskModal: React.FC<CreateTaskModalProps> = ({ isOpen, onClose, onSu
           }
         }
 
-        await axios.post('/api/scheduled-tasks/', payload);
+        await axios.post('/scheduled-tasks/', payload);
         toast.success('Scheduled task created');
       }