* fix(desktop): treat unpublished updates as unavailable
GitHub releases can become visible before their platform updater manifests finish publishing. Treat that specific upstream condition as an unavailable update while preserving Paseo reporting for genuine updater failures.
* refactor(desktop): inject updater runtime dependency
Exercise updater event and rejection behavior through a typed fake at the runtime boundary instead of coordinating a hoisted module singleton in tests.
* fix(desktop): preserve lazy updater initialization
* revert(desktop): drop updater runtime refactor