[ zapstore/zapstore ] Hotfix startup crash: defer router sync to avoid modifying provider during build

GoRouter's delegate notifies listeners during the widget tree build phase.
Since 83a74ceb, syncInstalledPackages() fires on every navigation (including
initial route), modifying state synchronously before its first await.
Wrap in Future.microtask() to defer past the build.
https://github.com/zapstore/zapstore/commit/817e49f59a723c417d19140e49f7416a998cb2df