Phase 3 Step 6: Complete Scheduler Integration with Bug Fixes

Implemented complete scheduler integration with automatic schedule loading,
orphaned scan cleanup, and conversion to local timezone for better UX.

Backend Changes:
- Added load_schedules_on_startup() to load enabled schedules on app start
- Implemented cleanup_orphaned_scans() to handle crashed/interrupted scans
- Converted scheduler from UTC to local system timezone throughout
- Enhanced scheduler service with robust error handling and logging

Frontend Changes:
- Updated all schedule UI templates to display local time instead of UTC
- Improved timezone indicators and user messaging
- Removed confusing timezone converter (no longer needed)
- Updated quick templates and help text for local time

Bug Fixes:
- Fixed critical timezone bug causing cron expressions to run at wrong times
- Fixed orphaned scans stuck in 'running' status after system crashes
- Improved time display clarity across all schedule pages

All schedules now use local system time for intuitive scheduling.

web/templates/schedules.html

@@ -107,6 +107,9 @@ function formatRelativeTime(timestamp) {
     const diffHours = Math.floor(diffMs / 3600000);
     const diffDays = Math.floor(diffMs / 86400000);
 
+    // Get local time string for tooltip/fallback
+    const localStr = date.toLocaleString();
+
     if (diffMs < 0) {
         // Past time
         const absDiffMinutes = Math.abs(diffMinutes);
@@ -120,7 +123,7 @@ function formatRelativeTime(timestamp) {
         if (absDiffHours < 24) return `${absDiffHours} hours ago`;
         if (absDiffDays === 1) return 'Yesterday';
         if (absDiffDays < 7) return `${absDiffDays} days ago`;
-        return date.toLocaleString();
+        return `<span title="${localStr}">${absDiffDays} days ago</span>`;
     } else {
         // Future time
         if (diffMinutes < 1) return 'In less than a minute';
@@ -130,7 +133,7 @@ function formatRelativeTime(timestamp) {
         if (diffHours < 24) return `In ${diffHours} hours`;
         if (diffDays === 1) return 'Tomorrow';
         if (diffDays < 7) return `In ${diffDays} days`;
-        return date.toLocaleString();
+        return `<span title="${localStr}">In ${diffDays} days</span>`;
     }
 }