feat: Enhance Uptime heartbeat bar

- Frontend: Increase heartbeat history to 60 items (1 hour)
- Frontend: Add empty bars for alignment when history is sparse
- Frontend: Improve tooltips with detailed status info
- Frontend: Update API client to support limit parameter

frontend/src/api/uptime.ts

@@ -26,7 +26,7 @@ export const getMonitors = async () => {
   return response.data;
 };
 
-export const getMonitorHistory = async (id: string) => {
-  const response = await client.get<UptimeHeartbeat[]>(`/uptime/monitors/${id}/history`);
+export const getMonitorHistory = async (id: string, limit: number = 50) => {
+  const response = await client.get<UptimeHeartbeat[]>(`/uptime/monitors/${id}/history?limit=${limit}`);
   return response.data;
 };