Some Microsoft accounts get a delegation-compact (d=) ticket, which the
pinned Xbox backend (Nexus 0.2.8) rejected: the library stayed empty
(store-ticket-format) and downloads failed. This moves the backend to
Nexus 0.2.12, which has the upstream store-ticket fix, rebases the
DroidDeck credentials, launch-view and cloud-token patches, and strips
the d= prefix from compact JWE tickets so downloads work again.
Tested by seven users in the Discord Xbox Store Issues thread on the
pr-1729 build at d55e05a0.
* Update Xbox backend to 0.2.12
* Fix cloud offering fallback and add regression tests
* Fix Xbox authentication with compact JWE tickets
* Restrict Xbox credentials to host backends and lease game launches
* Verify mapped PRoot backend images and retry lease heartbeat timeouts
* Bound Xbox backend shutdown and isolate service socket lifetimes
* Keep unique Xbox service sockets within Unix address limits
* Own licensed launch directories and recover abandoned views safely
* Serialize Xbox account revocation with sign-in commits and launch authorization
devSharaku