[Enhancement] Look for duplicated code and minimize it

[4cecoder]

[4cecoder]

Addressed the clearest case in PR #66: the repeated write-and-swallow-error pattern across the CRUD handler stubs (add/get/edit/delete) is now one shared handlers.writeString helper. app/settings.go's repeated per-field Check*/Get*/Set*/Show* pattern was left alone — it's more boilerplate-by-design than harmful duplication.

[4cecoder]

Closing — resolved by #66.