fix(studio): audit batch — debug.echo install, copyable errors, fast Diagnose

From a live-test audit:
- Install via the flow-editor 'Fix' sent 'debug.echo@^0' (version
  constraint included) as the install source; the hub resolves by bare
  name so it missed ('no store entry for debug.echo@^0'). Strip the
  @<constraint> like the Store page does — debug.echo now installs.
- Errors the operator could not copy: route the daemon-start failure
  (its stderr!), the flow-editor install failure and the federation
  issue failure through showFaiErrorSnack / a new showFaiProcessError
  helper, so every error is selectable, one-tap copyable and logged.
- Diagnose page opened slowly because doctor() Future.wait-ed on a live
  manifest fetch (8s server timeout); cap that one check at 2s so the
  page no longer waits on the network.

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

lib/pages/federation.dart

@@ -5,6 +5,7 @@ import '../data/hub.dart';
 import '../l10n/app_localizations.dart';
 import '../theme/theme.dart';
 import '../theme/tokens.dart';
+import '../data/error_presentation.dart';
 import '../widgets/widgets.dart';
 import 'welcome.dart' show showFaiDoc;
 
@@ -48,9 +49,8 @@ class _FederationPageState extends State<FederationPage> {
       _refresh();
     } catch (e) {
       if (!mounted) return;
-      ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(content: Text(l.federationIssueFailed(e.toString()))),
-      );
+      showFaiErrorSnack(context, 'federation.issue', e,
+          title: l.federationIssueFailed(''));
     }
   }