feat: implement hotspot calculation system with scheduled jobs

- Add hotspot calculation methods to analytics service
- Implement MySQL spatial queries for clustering (5+ reports within 500m)
- Calculate severity scores based on report count and frequency
- Create GET /api/analytics/hotspots endpoint
- Create GET /api/analytics/hotspots/:id endpoint for details
- Create POST /api/analytics/hotspots/calculate for manual trigger
- Implement scheduled job with node-cron (runs every 5 minutes)
- Add comprehensive test scripts for hotspot functionality
- Create detailed implementation documentation

Requirements addressed:
- 3.2: Identify areas with 5+ reports within 500m radius
- 3.3: Rank hotspots by severity score
- 3.4: Update calculations within 5 minutes
- 3.5: Provide data for map visualization with severity indicators

server/src/services/scheduledJobs.ts

@@ -0,0 +1,53 @@
+/**
+ * Scheduled Jobs Service
+ * Manages periodic tasks using node-cron
+ * 
+ * Requirement 3.4: Update Litter Hotspot calculations within 5 minutes of new report submissions
+ */
+
+import cron, { ScheduledTask } from 'node-cron';
+import { analyticsService } from './analyticsService';
+
+/**
+ * Initialize all scheduled jobs
+ */
+export function initializeScheduledJobs() {
+  console.log('[Scheduled Jobs] Initializing scheduled jobs...');
+
+  // Hotspot calculation job - runs every 5 minutes
+  // Requirement 3.4: Update hotspot calculations within 5 minutes
+  const hotspotJob = cron.schedule('*/5 * * * *', async () => {
+    try {
+      console.log('[Scheduled Jobs] Running hotspot calculation...');
+      const result = await analyticsService.calculateAndUpdateHotspots();
+      console.log(`[Scheduled Jobs] Hotspot calculation completed: ${result.hotspotsCalculated} hotspots calculated`);
+    } catch (error: any) {
+      console.error('[Scheduled Jobs] Error in hotspot calculation job:', error.message);
+    }
+  });
+
+  console.log('[Scheduled Jobs] ✓ Hotspot calculation job scheduled (every 5 minutes)');
+
+  // Return job instances for potential management
+  return {
+    hotspotJob,
+  };
+}
+
+/**
+ * Stop all scheduled jobs
+ * Useful for graceful shutdown
+ */
+export function stopScheduledJobs(jobs: { hotspotJob: ScheduledTask }) {
+  console.log('[Scheduled Jobs] Stopping all scheduled jobs...');
+  
+  if (jobs.hotspotJob) {
+    jobs.hotspotJob.stop();
+    console.log('[Scheduled Jobs] ✓ Hotspot calculation job stopped');
+  }
+}
+
+export default {
+  initializeScheduledJobs,
+  stopScheduledJobs,
+};