feat: show plugin diagnostics only in debug mode

frontend/src/App.svelte

@@ -219,6 +219,7 @@
       const settings = await App.GetAppSettings();
       debug.log('[App] checkVault: GetAppSettings returned', settings);
       flog('checkVault: GetAppSettings returned');
+      if (settings?.debug) debug.enable();
 
       debug.log('[App] checkVault: calling GetVaultStatus...');
       vaultStatus = await App.GetVaultStatus() || { status: 'unknown', path: '', vaultId: '' };

internal/api/app.go

@@ -2067,6 +2067,7 @@ func (a *App) GetAppSettings() map[string]interface{} {
 		"theme":            cfg.Theme,
 		"language":         cfg.Language,
 		"devMode":          cfg.DevMode,
+		"debug":            a.debug,
 		"userPluginsDir":   cfg.UserPluginsDir,
 		"lastOpenedAt":     cfg.LastOpenedAt,
 	}

internal/api/app_test.go

@@ -1791,11 +1791,14 @@ func TestAppSettingsLanguageAPI(t *testing.T) {
 	if err := settings.Update(&appsettings.Config{Theme: "light", DevMode: true}); err != nil {
 		t.Fatal(err)
 	}
-	app := &App{appSettings: settings}
+	app := &App{appSettings: settings, debug: true}
 
 	if got := app.GetAppSettings()["language"]; got != "system" {
 		t.Fatalf("initial language = %#v, want system", got)
 	}
+	if got := app.GetAppSettings()["debug"]; got != true {
+		t.Fatalf("debug = %#v, want true", got)
+	}
 	if errStr := app.UpdateAppSettings(map[string]interface{}{"language": "ru"}); errStr != "" {
 		t.Fatalf("UpdateAppSettings language: %s", errStr)
 	}