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/services/scheduler_service.py

@@ -6,7 +6,7 @@ scan execution and future scheduled scanning capabilities.
 """
 
 import logging
-from datetime import datetime
+from datetime import datetime, timezone
 from typing import Optional
 
 from apscheduler.schedulers.background import BackgroundScheduler
@@ -63,11 +63,13 @@ class SchedulerService:
             'misfire_grace_time': 60  # Allow 60 seconds for delayed starts
         }
 
-        # Create scheduler
+        # Create scheduler with local system timezone
+        # This allows users to schedule jobs using their local time
+        # APScheduler will automatically use the system's local timezone
         self.scheduler = BackgroundScheduler(
             executors=executors,
-            job_defaults=job_defaults,
-            timezone='UTC'
+            job_defaults=job_defaults
+            # timezone defaults to local system timezone
         )
 
         # Start scheduler
@@ -90,6 +92,63 @@ class SchedulerService:
             logger.info("APScheduler shutdown complete")
             self.scheduler = None
 
+    def load_schedules_on_startup(self):
+        """
+        Load all enabled schedules from database and register with APScheduler.
+
+        Should be called after init_scheduler() to restore scheduled jobs
+        that were active when the application last shutdown.
+
+        Raises:
+            RuntimeError: If scheduler not initialized
+        """
+        if not self.scheduler:
+            raise RuntimeError("Scheduler not initialized. Call init_scheduler() first.")
+
+        # Import here to avoid circular imports
+        from sqlalchemy import create_engine
+        from sqlalchemy.orm import sessionmaker
+        from web.models import Schedule
+
+        try:
+            # Create database session
+            engine = create_engine(self.db_url)
+            Session = sessionmaker(bind=engine)
+            session = Session()
+
+            try:
+                # Query all enabled schedules
+                enabled_schedules = (
+                    session.query(Schedule)
+                    .filter(Schedule.enabled == True)
+                    .all()
+                )
+
+                logger.info(f"Loading {len(enabled_schedules)} enabled schedules on startup")
+
+                # Register each schedule with APScheduler
+                for schedule in enabled_schedules:
+                    try:
+                        self.add_scheduled_scan(
+                            schedule_id=schedule.id,
+                            config_file=schedule.config_file,
+                            cron_expression=schedule.cron_expression
+                        )
+                        logger.info(f"Loaded schedule {schedule.id}: '{schedule.name}'")
+                    except Exception as e:
+                        logger.error(
+                            f"Failed to load schedule {schedule.id} ('{schedule.name}'): {str(e)}",
+                            exc_info=True
+                        )
+
+                logger.info("Schedule loading complete")
+
+            finally:
+                session.close()
+
+        except Exception as e:
+            logger.error(f"Error loading schedules on startup: {str(e)}", exc_info=True)
+
     def queue_scan(self, scan_id: int, config_file: str) -> str:
         """
         Queue a scan for immediate background execution.
@@ -142,9 +201,11 @@ class SchedulerService:
 
         from apscheduler.triggers.cron import CronTrigger
 
-        # Create cron trigger from expression
+        # Create cron trigger from expression using local timezone
+        # This allows users to specify times in their local timezone
         try:
             trigger = CronTrigger.from_crontab(cron_expression)
+            # timezone defaults to local system timezone
         except (ValueError, KeyError) as e:
             raise ValueError(f"Invalid cron expression '{cron_expression}': {str(e)}")