feat: implement automation module

- Event-based triggers (Phase 1):
  - Trigger/TriggerLog models with field_change type
  - TriggerService for condition evaluation and action execution
  - Trigger CRUD API endpoints
  - Task integration (status, assignee, priority changes)
  - Frontend: TriggerList, TriggerForm components

- Weekly reports (Phase 2):
  - ScheduledReport/ReportHistory models
  - ReportService for stats generation
  - APScheduler for Friday 16:00 job
  - Report preview/generate/history API
  - Frontend: WeeklyReportPreview, ReportHistory components

- Tests: 23 new tests (14 triggers + 9 reports)
- OpenSpec: add-automation change archived

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/core/scheduler.py

@@ -0,0 +1,53 @@
+import logging
+from apscheduler.schedulers.asyncio import AsyncIOScheduler
+from apscheduler.triggers.cron import CronTrigger
+
+from app.core.database import SessionLocal
+from app.services.report_service import ReportService
+
+logger = logging.getLogger(__name__)
+
+scheduler = AsyncIOScheduler()
+
+
+async def weekly_report_job():
+    """Job function to generate weekly reports."""
+    logger.info("Starting weekly report generation...")
+
+    db = SessionLocal()
+    try:
+        generated_for = await ReportService.generate_all_weekly_reports(db)
+        logger.info(f"Weekly reports generated for {len(generated_for)} users")
+    except Exception as e:
+        logger.error(f"Error generating weekly reports: {e}")
+    finally:
+        db.close()
+
+
+def init_scheduler():
+    """Initialize the scheduler with jobs."""
+    # Weekly report - Every Friday at 16:00
+    scheduler.add_job(
+        weekly_report_job,
+        CronTrigger(day_of_week='fri', hour=16, minute=0),
+        id='weekly_report',
+        name='Generate Weekly Reports',
+        replace_existing=True,
+    )
+
+    logger.info("Scheduler initialized with weekly report job (Friday 16:00)")
+
+
+def start_scheduler():
+    """Start the scheduler."""
+    if not scheduler.running:
+        init_scheduler()
+        scheduler.start()
+        logger.info("Scheduler started")
+
+
+def shutdown_scheduler():
+    """Shutdown the scheduler gracefully."""
+    if scheduler.running:
+        scheduler.shutdown(wait=False)
+        logger.info("Scheduler shutdown")