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/api/tasks/router.py

@@ -14,6 +14,7 @@ from app.middleware.auth import (
 )
 from app.middleware.audit import get_audit_metadata
 from app.services.audit_service import AuditService
+from app.services.trigger_service import TriggerService
 
 router = APIRouter(tags=["tasks"])
 
@@ -271,7 +272,7 @@ async def update_task(
             detail="Permission denied",
         )
 
-    # Capture old values for audit
+    # Capture old values for audit and triggers
     old_values = {
         "title": task.title,
         "description": task.description,
@@ -289,7 +290,7 @@ async def update_task(
         else:
             setattr(task, field, value)
 
-    # Capture new values for audit
+    # Capture new values for audit and triggers
     new_values = {
         "title": task.title,
         "description": task.description,
@@ -313,6 +314,10 @@ async def update_task(
             request_metadata=get_audit_metadata(request),
         )
 
+    # Evaluate triggers for priority changes
+    if "priority" in update_data:
+        TriggerService.evaluate_triggers(db, task, old_values, new_values, current_user)
+
     db.commit()
     db.refresh(task)
 
@@ -397,6 +402,9 @@ async def update_task_status(
             detail="Status not found in this project",
         )
 
+    # Capture old status for triggers
+    old_status_id = task.status_id
+
     task.status_id = status_data.status_id
 
     # Auto-set blocker_flag based on status name
@@ -405,6 +413,15 @@ async def update_task_status(
     else:
         task.blocker_flag = False
 
+    # Evaluate triggers for status changes
+    if old_status_id != status_data.status_id:
+        TriggerService.evaluate_triggers(
+            db, task,
+            {"status_id": old_status_id},
+            {"status_id": status_data.status_id},
+            current_user
+        )
+
     db.commit()
     db.refresh(task)
 
@@ -460,6 +477,15 @@ async def assign_task(
         request_metadata=get_audit_metadata(request),
     )
 
+    # Evaluate triggers for assignee changes
+    if old_assignee_id != assign_data.assignee_id:
+        TriggerService.evaluate_triggers(
+            db, task,
+            {"assignee_id": old_assignee_id},
+            {"assignee_id": assign_data.assignee_id},
+            current_user
+        )
+
     db.commit()
     db.refresh(task)