The DApps catalog lived only in memory and every read waited on first(), so
with the catalog URL unreachable the DApps screen waited forever.
feature-dapp-impl now bundles dapps_full.json at build time. On the first
sync the repository tries the network once and, if that fails, publishes the
bundled catalog so every read returns; the fetched catalog replaces it as
soon as it arrives.
The download task moves to scripts/bundled-config.gradle and serves both
the chain list and the DApps catalog. runtime and feature-dapp-impl unit
tests return defaults for android.util.Log, which the fallback calls.
