fix(web): elements of create item request repeated

improve(database): remove foreign keys

chore(web): change default sorting to update at

feat(web): detect repeated matched_text for item

fix(queue): date_end is not updated

improve(queue): add lock for completing task

fix(queue): date_end updating logics

fix(web): item can not create without schedule id

fix(web): item can not create without schedule id

feat(web): add download task dialog