Summary: Update the `.arcconfig` file to point to our decided-upon URL for hosting Refs T15006 Test Plan: I used `arc which` and verified it identified `https://we.phorge.it`: ```lang=console REPOSITORY To identify the repository associated with this working copy, arc followed this process: Configuration value "repository.callsign" is empty. This repository has no VCS UUID (this is normal for git/hg). The remote URI for this working copy is "ssh://git@we.phorge.it/source/phorge.git". Found a unique matching repository. This working copy is associated with the Phorge repository. ``` Reviewers: avivey, chris, tobiaswiese Reviewed By: avivey, tobiaswiese Maniphest Tasks: T15006 Differential Revision: https://we.phorge.it/D25001