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/modules.dart

@@ -45,7 +45,7 @@ class _ModulesPageState extends State<ModulesPage> {
         actions: [
           IconButton(
             icon: const Icon(Icons.refresh, size: 18),
-            tooltip: 'Reload',
+            tooltip: AppLocalizations.of(context)!.modulesReloadTooltip,
             onPressed: _refresh,
           ),
           const SizedBox(width: FaiSpace.sm),
@@ -54,6 +54,7 @@ class _ModulesPageState extends State<ModulesPage> {
       body: FutureBuilder<List<ModuleSummary>>(
         future: _future,
         builder: (context, snapshot) {
+          final l = AppLocalizations.of(context)!;
           if (snapshot.connectionState == ConnectionState.waiting) {
             return const Center(child: CircularProgressIndicator());
           }
@@ -61,22 +62,20 @@ class _ModulesPageState extends State<ModulesPage> {
             return FaiEmptyState(
               icon: Icons.cloud_off_outlined,
               iconColor: Theme.of(context).colorScheme.error,
-              title: 'Hub unreachable',
-              hint:
-                  'Start the hub with `fai serve`. Studio will retry automatically.',
+              title: l.hubUnreachable,
+              hint: l.hubUnreachableHint,
               action: FilledButton.tonal(
                 onPressed: _refresh,
-                child: const Text('Retry'),
+                child: Text(l.buttonRetry),
               ),
             );
           }
           final modules = snapshot.data ?? [];
           if (modules.isEmpty) {
-            return const FaiEmptyState(
+            return FaiEmptyState(
               icon: Icons.extension_outlined,
-              title: 'No modules yet',
-              hint:
-                  'Run `fai install <capability-name>` or check ~/.fai/modules/.',
+              title: l.modulesNoneTitle,
+              hint: l.modulesNoneHint,
             );
           }
           return ListView(
@@ -142,7 +141,7 @@ class _ModuleCard extends StatelessWidget {
               SizedBox(
                 width: 110,
                 child: Text(
-                  'Capabilities',
+                  AppLocalizations.of(context)!.modulesCapabilitiesLabel,
                   style: theme.textTheme.labelSmall?.copyWith(
                     color: theme.colorScheme.onSurfaceVariant,
                     letterSpacing: 0.4,
@@ -212,7 +211,7 @@ class _RecentActivityPanel extends StatelessWidget {
                   ),
                   const SizedBox(width: 6),
                   Text(
-                    'RECENT ACTIVITY',
+                    AppLocalizations.of(context)!.modulesRecentActivity,
                     style: theme.textTheme.labelSmall?.copyWith(
                       color: theme.colorScheme.onSurfaceVariant,
                       letterSpacing: 0.6,
@@ -221,7 +220,8 @@ class _RecentActivityPanel extends StatelessWidget {
                   ),
                   const SizedBox(width: FaiSpace.sm),
                   Text(
-                    'last ${events.length} install/uninstall events from the audit log',
+                    AppLocalizations.of(context)!
+                        .modulesRecentActivityHint(events.length),
                     style: theme.textTheme.bodySmall?.copyWith(
                       color: theme.colorScheme.onSurfaceVariant,
                     ),
@@ -269,7 +269,7 @@ class _ActivityRow extends StatelessWidget {
           ),
           Expanded(
             child: Text(
-              '${installed ? "installed" : "uninstalled"} '
+              '${installed ? AppLocalizations.of(context)!.modulesActivityInstalled : AppLocalizations.of(context)!.modulesActivityUninstalled} '
               '${event.moduleName ?? "(unknown)"}'
               '${event.moduleVersion != null ? " v${event.moduleVersion}" : ""}',
               style: theme.textTheme.bodySmall,