Fixes adding Microsoft 365 and Exchange accounts through Thunderbird's built-in Outlook Web login. The Conditional Access error 530003 ("device is not registered") no longer occurs: Thunderbird opens that login in an isolated cookie container that the single sign-on cookie did not reach before, and the cookie is now provided there so Entra recognises the device.

Adds an options page in Thunderbird (previously available only on Firefox and Chromium), including a working opt-in device compliance toggle.

Fixes the companion native messaging host installation on RHEL, Fedora and openSUSE (lib64 path), where single sign-on could previously fail silently.