feat(phase3): import/export, sparklines, user theme overrides

- JSON import/export with conflict resolution (skip/overwrite) + admin UI
- Ping history sparklines on AppWidget and AppCard (24h, 288 points)
- Hourly cleanup job for old AppStatus records
- User theme preferences (hue, saturation, mode, background, locale)
- Settings page with ThemeCustomizer (sliders, toggles, live preview)
- Prisma migration for user preference fields
- i18n translations for all new strings (EN/RU)

src/lib/server/jobs/healthcheckScheduler.ts

@@ -1,11 +1,13 @@
 import cron from 'node-cron';
-import { checkAllApps } from '$lib/server/services/healthcheckService.js';
+import { checkAllApps, pruneOldStatuses } from '$lib/server/services/healthcheckService.js';
 
 let scheduledTask: cron.ScheduledTask | null = null;
+let cleanupTask: cron.ScheduledTask | null = null;
 
 /**
  * Start the healthcheck scheduler.
  * Runs checkAllApps on a cron schedule (default: every 60 seconds).
+ * Also starts an hourly cleanup job to prune old status records.
  */
 export function startScheduler(cronExpression: string = '* * * * *'): void {
 	if (scheduledTask) {
@@ -20,6 +22,15 @@ export function startScheduler(cronExpression: string = '* * * * *'): void {
 		}
 	});
 
+	// Cleanup job: run every hour at minute 0
+	cleanupTask = cron.schedule('0 * * * *', async () => {
+		try {
+			await pruneOldStatuses();
+		} catch {
+			// Swallow errors to prevent scheduler crash
+		}
+	});
+
 	// Run an initial check shortly after startup
 	setTimeout(() => {
 		checkAllApps().catch(() => {
@@ -29,11 +40,15 @@ export function startScheduler(cronExpression: string = '* * * * *'): void {
 }
 
 /**
- * Stop the healthcheck scheduler.
+ * Stop the healthcheck scheduler and cleanup job.
  */
 export function stopScheduler(): void {
 	if (scheduledTask) {
 		scheduledTask.stop();
 		scheduledTask = null;
 	}
+	if (cleanupTask) {
+		cleanupTask.stop();
+		cleanupTask = null;
+	}
 }