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/pages/store.dart

@@ -10,6 +10,7 @@ import 'package:flutter_markdown/flutter_markdown.dart';
 
 import '../data/hub.dart';
 import '../data/system_actions.dart';
+import '../l10n/app_localizations.dart';
 import '../theme/theme.dart';
 import '../theme/tokens.dart';
 import '../widgets/widgets.dart';
@@ -220,9 +221,25 @@ class _StorePageState extends State<StorePage> {
                       _status.isEmpty &&
                       !_installedOnly &&
                       items.any((e) => e.featured);
+                  // Sparse-store nudge: when no filter is set
+                  // and the store carries no federated entries,
+                  // hint that adding an MCP / n8n endpoint
+                  // brings dozens of capabilities at once.
+                  // Hides the moment any federated entry shows
+                  // up — the nudge has done its job.
+                  final showFederationNudge =
+                      _queryCtrl.text.trim().isEmpty &&
+                      _category.isEmpty &&
+                      _status.isEmpty &&
+                      !_installedOnly &&
+                      !items.any((e) => e.isFederated);
                   return Column(
                     crossAxisAlignment: CrossAxisAlignment.start,
                     children: [
+                      if (showFederationNudge) ...[
+                        const _FederationNudge(),
+                        const SizedBox(height: FaiSpace.md),
+                      ],
                       if (showFeatured) ...[
                         _FeaturedStrip(
                           items: items.where((e) => e.featured).toList(),
@@ -1773,3 +1790,66 @@ class _ScreenshotPlaceholder extends StatelessWidget {
     );
   }
 }
+
+/// Sparse-store nudge: the operator's store has only the
+/// bundled native + planned modules and no federated entries.
+/// The single biggest store-fullness lever is configuring an
+/// MCP server or n8n endpoint, so the banner says exactly
+/// that. Tap → Settings dialog opens straight to the editor.
+/// Dismisses automatically the next render after a federated
+/// entry shows up — no per-user "don't show again".
+class _FederationNudge extends StatelessWidget {
+  const _FederationNudge();
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final l = AppLocalizations.of(context)!;
+    return Container(
+      width: double.infinity,
+      padding: const EdgeInsets.all(FaiSpace.md),
+      decoration: BoxDecoration(
+        color: theme.colorScheme.surfaceContainer,
+        borderRadius: BorderRadius.circular(FaiRadius.md),
+        border: Border.all(color: theme.colorScheme.outlineVariant),
+      ),
+      child: Row(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Icon(
+            Icons.hub_outlined,
+            size: 22,
+            color: theme.colorScheme.primary,
+          ),
+          const SizedBox(width: FaiSpace.md),
+          Expanded(
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                Text(
+                  l.storeFederationNudgeTitle,
+                  style: theme.textTheme.titleSmall?.copyWith(
+                    fontWeight: FontWeight.w600,
+                  ),
+                ),
+                const SizedBox(height: 4),
+                Text(
+                  l.storeFederationNudgeBody,
+                  style: theme.textTheme.bodySmall?.copyWith(
+                    color: theme.colorScheme.onSurfaceVariant,
+                  ),
+                ),
+              ],
+            ),
+          ),
+          const SizedBox(width: FaiSpace.md),
+          FilledButton.tonalIcon(
+            onPressed: () => FaiSettingsDialog.show(context),
+            icon: const Icon(Icons.settings_outlined, size: 16),
+            label: Text(l.storeFederationNudgeButton),
+          ),
+        ],
+      ),
+    );
+  }
+}