fix(studio): theme picker confirms applied + surfaces load failures

Two operator-visible fixes prompted by 'I picked a theme but
nothing changed':

  - Theme picker tile taps now show a brief "Theme applied:
    <name>" snackbar — the picker applies themes instantly, so
    the operator needs a confirming cue. Slow `_pluginThemes`
    loads no longer read as "click did nothing".
  - `_pluginThemes` failures (plugin unreachable, manifest
    drift, etc.) write to `FaiLog` so `fai admin doctor` and
    Studio's inline log viewer can surface them. Previously
    swallowed silently, which is what made debugging this so
    miserable.
  - Settings dialog's primary button relabelled to
    "Connect to endpoint" (was "Save & connect") so operators
    don't mistake it for "save my theme choice". The theme
    selection persists at tile-tap time; the Settings dialog
    has nothing left to "save".
  - Theme section header gains an explicit "(applies instantly)"
    cue for the same reason.

Also fixes a pre-existing curly-braces lint in the n8n add-
endpoint dialog. Studio bumped to 0.62.1, editor pinned via
path override at 0.15.1.

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

lib/l10n/app_de.arb

@@ -104,7 +104,14 @@
   "mcpSuggestionMemoryDesc": "Anthropic — persistenter Knowledge-Graph als Agenten-Gedächtnis.",
   "mcpSuggestionTimeDesc": "Anthropic — aktuelle Uhrzeit + Zeitzonen-Konvertierung.",
   "mcpServerEnLanguageBadge": "Server-Text in Englisch — Studio zeigt ihn wie geliefert.",
-  "themePluginHeader": "Theme-Plugin",
+  "themePluginHeader": "Theme-Plugin (wirkt sofort)",
+  "themeApplied": "Theme aktiv: {name}",
+  "@themeApplied": {
+    "placeholders": {
+      "name": {"type": "String"}
+    }
+  },
+  "themePluginFailed": "Theme-Plugin konnte nicht geladen werden — vorheriges Theme bleibt.",
   "themePluginNone": "Standard (kein Plugin)",
   "themePluginHint": "Built-in- und Plugin-Kacheln bringen handkuratierte Paletten mit. Die Kachel „Eigene Farbe\" leitet aus einer gewählten Seedfarbe eine vollständige Material-3-Palette ab (primary, secondary, tertiary, surface, …) — das ist ein vollwertiges Theme, kein Einzelfarb-Tweak.",
   "themePluginEmpty": "Kein Theme-Plugin installiert. Im Store eines aus der Kategorie studio-plugin auswählen.",
@@ -118,7 +125,7 @@
   "settingsHost": "Host",
   "settingsPort": "Port",
   "settingsTls": "TLS",
-  "settingsSaveAndConnect": "Speichern & verbinden",
+  "settingsSaveAndConnect": "Mit Endpoint verbinden",
   "settingsLanguage": "Sprache",
   "settingsLanguageHint": "Sprache der App. Wirkt auf alle Seiten; mehrsprachige Store-Einträge folgen ebenfalls.",
   "settingsHubEndpointHint": "Wohin soll Studio sich verbinden? Standard ist der lokale Hub auf 127.0.0.1:50051.",

lib/l10n/app_en.arb

@@ -107,7 +107,14 @@
   "mcpSuggestionMemoryDesc": "Anthropic — persistent knowledge graph for an agent's memory.",
   "mcpSuggestionTimeDesc": "Anthropic — current time + timezone conversion.",
   "mcpServerEnLanguageBadge": "Server text in English — Studio shows it as supplied.",
-  "themePluginHeader": "Theme plugin",
+  "themePluginHeader": "Theme plugin (applies instantly)",
+  "themeApplied": "Theme applied: {name}",
+  "@themeApplied": {
+    "placeholders": {
+      "name": {"type": "String"}
+    }
+  },
+  "themePluginFailed": "Theme plugin could not load — keeping previous theme.",
   "themePluginNone": "Built-in (no plugin)",
   "themePluginHint": "Built-in and plugin tiles ship hand-curated palettes. The Custom tile derives a full Material 3 palette (primary, secondary, tertiary, surface, …) from one seed colour you pick — it's a complete theme, not a single-colour tweak.",
   "themePluginEmpty": "No theme plugins installed. Open the Store and pick one in the studio-plugin category.",
@@ -121,7 +128,7 @@
   "settingsHost": "Host",
   "settingsPort": "Port",
   "settingsTls": "TLS",
-  "settingsSaveAndConnect": "Save & connect",
+  "settingsSaveAndConnect": "Connect to endpoint",
   "settingsLanguage": "Language",
   "settingsLanguageHint": "App language. Affects every page; bilingual store entries also flip via this toggle.",
   "settingsHubEndpointHint": "Where should Studio connect? Default is the local hub at 127.0.0.1:50051.",

lib/l10n/app_localizations.dart

@@ -641,9 +641,21 @@ abstract class AppLocalizations {
   /// No description provided for @themePluginHeader.
   ///
   /// In en, this message translates to:
-  /// **'Theme plugin'**
+  /// **'Theme plugin (applies instantly)'**
   String get themePluginHeader;
 
+  /// No description provided for @themeApplied.
+  ///
+  /// In en, this message translates to:
+  /// **'Theme applied: {name}'**
+  String themeApplied(String name);
+
+  /// No description provided for @themePluginFailed.
+  ///
+  /// In en, this message translates to:
+  /// **'Theme plugin could not load — keeping previous theme.'**
+  String get themePluginFailed;
+
   /// No description provided for @themePluginNone.
   ///
   /// In en, this message translates to:
@@ -725,7 +737,7 @@ abstract class AppLocalizations {
   /// No description provided for @settingsSaveAndConnect.
   ///
   /// In en, this message translates to:
-  /// **'Save & connect'**
+  /// **'Connect to endpoint'**
   String get settingsSaveAndConnect;
 
   /// No description provided for @settingsLanguage.

lib/l10n/app_localizations_de.dart

@@ -313,7 +313,16 @@ class AppLocalizationsDe extends AppLocalizations {
       'Server-Text in Englisch — Studio zeigt ihn wie geliefert.';
 
   @override
-  String get themePluginHeader => 'Theme-Plugin';
+  String get themePluginHeader => 'Theme-Plugin (wirkt sofort)';
+
+  @override
+  String themeApplied(String name) {
+    return 'Theme aktiv: $name';
+  }
+
+  @override
+  String get themePluginFailed =>
+      'Theme-Plugin konnte nicht geladen werden — vorheriges Theme bleibt.';
 
   @override
   String get themePluginNone => 'Standard (kein Plugin)';
@@ -357,7 +366,7 @@ class AppLocalizationsDe extends AppLocalizations {
   String get settingsTls => 'TLS';
 
   @override
-  String get settingsSaveAndConnect => 'Speichern & verbinden';
+  String get settingsSaveAndConnect => 'Mit Endpoint verbinden';
 
   @override
   String get settingsLanguage => 'Sprache';

lib/l10n/app_localizations_en.dart

@@ -313,7 +313,16 @@ class AppLocalizationsEn extends AppLocalizations {
       'Server text in English — Studio shows it as supplied.';
 
   @override
-  String get themePluginHeader => 'Theme plugin';
+  String get themePluginHeader => 'Theme plugin (applies instantly)';
+
+  @override
+  String themeApplied(String name) {
+    return 'Theme applied: $name';
+  }
+
+  @override
+  String get themePluginFailed =>
+      'Theme plugin could not load — keeping previous theme.';
 
   @override
   String get themePluginNone => 'Built-in (no plugin)';
@@ -358,7 +367,7 @@ class AppLocalizationsEn extends AppLocalizations {
   String get settingsTls => 'TLS';
 
   @override
-  String get settingsSaveAndConnect => 'Save & connect';
+  String get settingsSaveAndConnect => 'Connect to endpoint';
 
   @override
   String get settingsLanguage => 'Language';

lib/main.dart

@@ -8,6 +8,7 @@ import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
+import 'data/fai_log.dart';
 import 'data/hub.dart';
 import 'data/system_actions.dart';
 import 'data/theme_plugin.dart';
@@ -26,7 +27,7 @@ import 'widgets/widgets.dart';
 /// Studio's own build version. Bump on every UI commit so the
 /// running app self-identifies — visible in the sidebar header
 /// and quick-glance proof that you're seeing the current build.
-const String kStudioVersion = '0.62.0';
+const String kStudioVersion = '0.62.1';
 
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
@@ -178,10 +179,18 @@ class StudioAppState extends State<StudioApp> {
             : themeDataFromScheme(schemes.light!),
         dark: schemes.dark == null ? null : themeDataFromScheme(schemes.dark!),
       );
-    } catch (_) {
-      // Plugin unreachable, hub down, etc. Fall back to
-      // FaiTheme defaults silently — the Settings dialog is
-      // where the operator surfaces / fixes the problem.
+    } catch (e) {
+      // Plugin unreachable, hub down, manifest schema drift —
+      // any of these end up here. Log the failure so doctor +
+      // the in-app log viewer can surface it; the picker's
+      // own "applied" snackbar is replaced upstream by the
+      // friendlier failure message via [themePluginFailed].
+      // ignore: discarded_futures
+      FaiLog.instance.error(
+        'theme.plugin.load',
+        e,
+        context: 'capability=$capability',
+      );
       return (light: null, dark: null);
     }
   }

lib/widgets/fai_settings_dialog.dart

@@ -1472,8 +1472,9 @@ class _AddN8nEndpointDialogState extends State<_AddN8nEndpointDialog> {
         ),
         FilledButton(
           onPressed: () {
-            if (_name.text.trim().isEmpty || _baseUrl.text.trim().isEmpty)
+            if (_name.text.trim().isEmpty || _baseUrl.text.trim().isEmpty) {
               return;
+            }
             Navigator.pop(
               context,
               N8nEndpointDraft(

lib/widgets/theme_picker_grid.dart

@@ -109,11 +109,29 @@ class _ThemePickerGridState extends State<ThemePickerGrid> {
       selected: active == null,
       onTap: () {
         StudioApp.of(context)?.setThemePlugin(null);
+        _confirmApplied(l, l.themePluginNone);
         setState(() {});
       },
     );
   }
 
+  /// Brief snackbar acknowledging the theme switch. The picker
+  /// applies themes instantly (no Save), so the operator needs
+  /// a visible cue that the click was registered — without it,
+  /// a slow theme load looks like "the click did nothing".
+  void _confirmApplied(AppLocalizations l, String displayName) {
+    final messenger = ScaffoldMessenger.maybeOf(context);
+    if (messenger == null) return;
+    messenger.removeCurrentSnackBar();
+    messenger.showSnackBar(
+      SnackBar(
+        content: Text(l.themeApplied(displayName)),
+        duration: const Duration(seconds: 2),
+        behavior: SnackBarBehavior.floating,
+      ),
+    );
+  }
+
   Widget _pluginTile(ThemeData theme, String cap, String? active) {
     // Pretty name: studio.theme.sunflower → "Sunflower".
     final display = _displayName(cap);
@@ -138,6 +156,7 @@ class _ThemePickerGridState extends State<ThemePickerGrid> {
       loading: preview == null,
       onTap: () {
         StudioApp.of(context)?.setThemePlugin(cap);
+        _confirmApplied(AppLocalizations.of(context)!, display);
         setState(() {});
       },
     );
@@ -176,6 +195,7 @@ class _ThemePickerGridState extends State<ThemePickerGrid> {
         // Strip alpha component — we only persist the RGB.
         final rgb = hex.substring(2).toUpperCase();
         StudioApp.of(context)?.setThemePlugin('custom:#$rgb');
+        _confirmApplied(l, '#$rgb');
         setState(() {});
       },
     );