Local viewer, deferred

The RFC looked at a local viewer that would open your repo's bundle straight in the app. It is feasible, but not cheap: the project pages would need to become static-export friendly, and the real work, a read-only data source fed by the repo bundle, is tangled with the move to IndexedDB and is best done once, after it.

Meanwhile, the existing "open in the app" path (validate, pack, hand off to arkaik.app) already covers the need. So the build was deferred, not dropped: small enabling refactors can land along the way, keeping the door open.