fix(auth): allow editing server during re-login

[okker24]

Summary

• allow the server/environment field to be edited during account re-login
• keep the account and local data in place while repairing a changed self-hosted endpoint

Why

A self-hosted server can move or change ports while an account is offline. Previously the re-login flow locked the server field, forcing users toward signing out and re-adding the account even when only the endpoint needed correction.

Test

• verified the common and desktop source sets compile as part of :common:desktopTest

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