feat(studio): Doctor + Modules localized + sparse-store federation nudge (v0.25.0)

Two threads.

Translation expansion: every visible string on the Doctor
page (section headers, status text, button labels, daemon-
control card, daemon-files panel, update banner) and the
Modules page (recent-activity strip, capabilities label,
uninstall dialog + toast) flips between DE and EN with the
sidebar toggle. Adds ~50 ARB keys split between
`app_en.arb` / `app_de.arb`. Pluralised + parametrised
strings (`{n} events verified`, `Running on {name}: {endpoint}`)
use the standard ICU placeholder syntax so future locales
slot in without code changes.

Sparse-store federation nudge: the Store page renders an
inline banner above the grid when the operator has zero
federated entries — single biggest store-fullness lever is
configuring an MCP server / n8n endpoint, so the banner
says exactly that and the button opens Settings straight
to the editor. Banner dismisses automatically the next
render after a federated entry appears.

Coverage stand for translation: Doctor + Modules + sidebar
+ page titles + nav + Cmd+K labels are bilingual. Settings
dialog, Approvals cards, Audit drilldown, MCP/n8n editors,
Store search hint + filter chips remain English-literal.
The infrastructure (ARB plumbing, generator hookup,
locale-notifier) means each follow-up surface is a
one-line ARB edit + one call-site swap.

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

lib/widgets/fai_module_sheet.dart

@@ -6,6 +6,7 @@
 import 'package:flutter/material.dart';
 
 import '../data/hub.dart';
+import '../l10n/app_localizations.dart';
 import '../theme/theme.dart';
 import '../theme/tokens.dart';
 import 'fai_pill.dart';
@@ -48,19 +49,16 @@ class _FaiModuleSheetState extends State<FaiModuleSheet> {
   }
 
   Future<void> _confirmAndUninstall(ModuleDetail detail) async {
+    final l = AppLocalizations.of(context)!;
     final ok = await showDialog<bool>(
       context: context,
       builder: (ctx) => AlertDialog(
-        title: const Text('Uninstall module?'),
-        content: Text(
-          'Removes ${detail.name} v${detail.version} from this hub. '
-          'Flows that reference it will fail at the next run. '
-          'A `module.uninstalled` audit event is recorded.',
-        ),
+        title: Text(l.modulesUninstallTitle),
+        content: Text(l.modulesUninstallBody(detail.name, detail.version)),
         actions: [
           TextButton(
             onPressed: () => Navigator.pop(ctx, false),
-            child: const Text('Cancel'),
+            child: Text(l.buttonCancel),
           ),
           FilledButton(
             onPressed: () => Navigator.pop(ctx, true),
@@ -68,7 +66,7 @@ class _FaiModuleSheetState extends State<FaiModuleSheet> {
               backgroundColor: Theme.of(ctx).colorScheme.error,
               foregroundColor: Theme.of(ctx).colorScheme.onError,
             ),
-            child: const Text('Uninstall'),
+            child: Text(l.buttonUninstall),
           ),
         ],
       ),
@@ -79,14 +77,16 @@ class _FaiModuleSheetState extends State<FaiModuleSheet> {
       final r = await HubService.instance.uninstallModule(detail.name);
       if (!mounted) return;
       ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(content: Text('Uninstalled ${r.name} v${r.version}.')),
+        SnackBar(
+          content: Text(l.modulesUninstalledToast(r.name, r.version)),
+        ),
       );
       Navigator.pop(context, true);
     } catch (e) {
       if (!mounted) return;
       setState(() => _uninstalling = false);
       ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(content: Text('Uninstall failed: $e')),
+        SnackBar(content: Text(l.modulesUninstallFailed(e.toString()))),
       );
     }
   }
@@ -269,7 +269,11 @@ class _Body extends StatelessWidget {
                       child: CircularProgressIndicator(strokeWidth: 2),
                     )
                   : const Icon(Icons.delete_outline, size: 16),
-              label: Text(uninstalling ? 'Uninstalling…' : 'Uninstall'),
+              label: Text(
+                uninstalling
+                    ? AppLocalizations.of(context)!.modulesUninstalling
+                    : AppLocalizations.of(context)!.buttonUninstall,
+              ),
               style: OutlinedButton.styleFrom(
                 foregroundColor: theme.colorScheme.error,
                 side: BorderSide(