A store icon in the Store app bar opens a dialog that lists the
configured module stores + the bundled seed (with per-source module
counts), lets the operator add a store by index URL (the hub fetches +
merges it live so its modules appear immediately), and remove a store.
Backed by the new ListStores/AddStore/RemoveStore RPCs + SDK methods.
This is how a domain app's published modules (e.g. reclaim's) become
visible in the Store without touching the CLI.
Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>
