feat(settings): multi-version uninstall picker + default_scope editor

Two operator surfaces shipped together:

**Multi-version uninstall picker** — when more than one version
of a `(provider, name)` is installed side-by-side, both the
module-sheet "Uninstall" affordance and the store-detail
"Uninstall" affordance now ask the operator which version to
remove before calling the RPC. The hub's wire-level support for
this (UninstallModuleRequest.version) was already there; Studio
just wasn't using it. Picker pre-selects the highest version so
single-version flows still take one click.

  - `HubService.installedVersions(name)` enumerates the installed
    versions via the capabilities list.
  - `HubService.uninstallModule(name, version: ...)` forwards
    the version into the RPC.
  - `_UninstallVersionPickerDialog` (module sheet) and
    `_StoreUninstallVersionPickerDialog` (store) host the
    picker — separate widgets so each surface can evolve copy
    independently. Uses `RadioGroup<String>` for Flutter
    3.32+ deprecation compliance.

**Default scope editor** — new DEFAULT SCOPE panel in Settings
that calls the freshly-added HubAdmin RPCs
`GetDefaultScope` / `SetDefaultScope`. Operators can:

  - reorder publisher segments with up/down buttons
    (first match wins in the bare-form resolver),
  - delete entries (hub still rejects empty list — Studio
    surfaces the constraint inline),
  - add arbitrary entries via the text field,
  - add catalog-known publishers via suggestion chips
    (sorted alphabetically, populated from the catalog).

Every change persists to `~/.fai/config.yaml` via the hub
and hot-swaps the in-memory copy without a daemon restart.

Bumped pubspec to 0.48.0. dart analyze clean (No issues
found!); flutter test green (11 tests).

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/l10n/app_localizations_en.dart

@@ -1303,6 +1303,46 @@ class AppLocalizationsEn extends AppLocalizations {
   String get storeAdvisoryVersionTooltip =>
       'Federated upstream service — version is advisory; the upstream may break compatibility without bumping it.';
 
+  @override
+  String get uninstallVersionPickerTitle => 'Pick a version to uninstall';
+
+  @override
+  String uninstallVersionPickerBody(String module) {
+    return 'Several versions of `$module` are installed side-by-side. Select the exact version to remove — the others stay in place.';
+  }
+
+  @override
+  String get uninstallVersionPickerContinue => 'Continue';
+
+  @override
+  String get defaultScopeHeader => 'DEFAULT SCOPE';
+
+  @override
+  String get defaultScopeBlurb =>
+      'Ordered list of publisher segments the hub consults when a flow names a capability without an explicit `<provider>/` prefix. First match wins — promote the segments your team uses most to the top. Catalog-known publishers appear as chips; arbitrary entries are accepted for private segments.';
+
+  @override
+  String get defaultScopeAddLabel => 'Add publisher segment';
+
+  @override
+  String get defaultScopeAddHint => 'e.g. acme.team';
+
+  @override
+  String get defaultScopeAddButton => 'Add';
+
+  @override
+  String get defaultScopeSuggestions => 'Catalog suggestions:';
+
+  @override
+  String get defaultScopeSavedToast => 'Default scope updated.';
+
+  @override
+  String get defaultScopeLoadFailed => 'Could not load default scope.';
+
+  @override
+  String get defaultScopeNonEmptyError =>
+      'Default scope cannot be empty — keep at least one segment.';
+
   @override
   String get maintenanceHeader => 'HUB MAINTENANCE';