feat: show tasks completed today

backend/recurrence_service.py

@@ -96,6 +96,10 @@ async def apply_task_changes(
             recurrence.starts_at = changes["due_at"]
 
     now = utcnow()
+    if changes.get("completed") is True and not task.completed:
+        changes["completed_at"] = now
+    elif changes.get("completed") is False:
+        changes["completed_at"] = None
     result = await db.execute(
         update(Task)
         .where(
@@ -120,6 +124,6 @@ async def apply_task_changes(
                 Task.deleted_at.is_(None),
                 Task.completed.is_(True),
             )
-            .values(completed=False, version=Task.version + 1, updated_at=now)
+            .values(completed=False, completed_at=None, version=Task.version + 1, updated_at=now)
         )
     return updated_task, changed