* feat(system): support for disabling public memos

* fix(web/editor): set visibility to private on disabled public memos

* feat(server/memo): find/check if public memos are disabled

* fix(server/memo): handle error for finding system error

* fix(server/memo): unmarshal visiblity when getting system settings

* chore(web): move side effect imports to end

* Update memo.go

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Co-authored-by: boojack <stevenlgtm@gmail.com>