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/data/hub.dart

@@ -391,13 +391,50 @@ class HubService {
 
   /// Remove an installed module by name. Returns the version
   /// that was removed so the caller can confirm.
+  ///
+  /// Pass [version] to target a specific version when multiple
+  /// versions of the same `(provider, name)` are installed
+  /// side-by-side. Empty / omitted lets the hub pick the
+  /// highest-version match.
   Future<({String name, String version})> uninstallModule(
-    String name,
-  ) async {
-    final r = await _client.uninstallModule(name);
+    String name, {
+    String version = '',
+  }) async {
+    final r = await _client.uninstallModule(name, version: version);
     return (name: r.name, version: r.version);
   }
 
+  /// Read the operator's `default_scope:` plus the catalog-known
+  /// publisher shortlist. Used by Settings → DEFAULT SCOPE panel.
+  Future<({List<String> scope, List<String> knownProviders})>
+      getDefaultScope() async {
+    return _client.getDefaultScope();
+  }
+
+  /// Replace the operator's `default_scope:` and hot-swap on the
+  /// running hub. Caller passes the new ordered list; hub rejects
+  /// an empty list with InvalidArgument.
+  Future<({List<String> scope, List<String> knownProviders})>
+      setDefaultScope(List<String> scope) async {
+    return _client.setDefaultScope(scope);
+  }
+
+  /// Every installed version of one module, sorted newest-last.
+  /// Returns an empty list when nothing matches. Used by the
+  /// uninstall flow to show a picker when more than one version
+  /// is installed side-by-side.
+  Future<List<String>> installedVersions(String moduleName) async {
+    final caps = await _client.listCapabilities();
+    final versions = caps
+        .where((c) => c.moduleName == moduleName)
+        .where((c) => c.kind.isEmpty || c.kind == 'wasm')
+        .map((c) => c.moduleVersion)
+        .toSet()
+        .toList()
+      ..sort();
+    return versions;
+  }
+
   /// Read the installed module's `MODULE.md` (or
   /// `MODULE.<locale>.md`) from disk under
   /// `~/.fai/modules/<module>/`. Air-gap friendly, no network.