[landing/lib/native/web] update copy for thread notifications for the rest of the app

Summary:
This diff updates the rest of the copy from "focused" => "home" and "background" => "muted"

Linear task: https://linear.app/comm/issue/ENG-8455/rename-focused-to-home-and-background-to-muted

Test Plan:
flow + please see the screenshots below

Reviewers: ashoat, inka

Reviewed By: ashoat, inka

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12684