feat(i18n): add Spanish, Italian, French and German locales

New locale files with translations for all existing message keys:
- es: Spanish (ES)
- it: Italian (IT)
- fr: French (FR)
- de: German (DE)

The locale is auto-detected from the system. Fallback chain:
LANG → user preference → ru (matched) → en (fallback)

locales/de/main.ftl

@@ -0,0 +1,13 @@
+cluster-not-found = Cluster "{ $name }" nicht gefunden
+nccl-config-missing = NCCL-Konfiguration nicht gefunden
+cluster-auto-fail = Kein geeigneter Cluster auswählbar
+cluster-selected = ✅ Cluster automatisch ausgewählt: { $name } ({ $nodes } Knoten)
+container-log-header = 📜 Letzte Container-Logs:
+cluster-stopping = 🛑 Cluster '{ $name }' wird gestoppt...
+cluster-all-stopped = ✅ Alle Container gestoppt.
+cluster-section = === Cluster: { $name } ===
+container-count = Container insgesamt: { $count }
+no-sm121-containers = (keine sm121-Container)
+docker-unavailable = ✗ Docker nicht verfügbar
+ssh-error = { $node } ({ $ip }): ✗ SSH-Fehler: { $error }
+task-join-error = ✗ Task-Join-Fehler: { $error }

locales/es/main.ftl

@@ -0,0 +1,13 @@
+cluster-not-found = Clúster "{ $name }" no encontrado
+nccl-config-missing = Configuración NCCL no encontrada
+cluster-auto-fail = No se pudo seleccionar un clúster adecuado
+cluster-selected = ✅ Clúster seleccionado automáticamente: { $name } ({ $nodes } nodos)
+container-log-header = 📜 Últimos registros del contenedor:
+cluster-stopping = 🛑 Deteniendo el clúster '{ $name }'...
+cluster-all-stopped = ✅ Todos los contenedores detenidos.
+cluster-section = === Clúster: { $name } ===
+container-count = Total de contenedores: { $count }
+no-sm121-containers = (sin contenedores sm121)
+docker-unavailable = ✗ Docker no disponible
+ssh-error = { $node } ({ $ip }): ✗ Error SSH: { $error }
+task-join-error = ✗ Error al unir tarea: { $error }

locales/fr/main.ftl

@@ -0,0 +1,13 @@
+cluster-not-found = Cluster "{ $name }" introuvable
+nccl-config-missing = Configuration NCCL introuvable
+cluster-auto-fail = Impossible de sélectionner un cluster approprié
+cluster-selected = ✅ Cluster sélectionné automatiquement : { $name } ({ $nodes } nœuds)
+container-log-header = 📜 Dernières journaux du conteneur :
+cluster-stopping = 🛑 Arrêt du cluster '{ $name }'...
+cluster-all-stopped = ✅ Tous les conteneurs arrêtés.
+cluster-section = === Cluster : { $name } ===
+container-count = Total des conteneurs : { $count }
+no-sm121-containers = (aucun conteneur sm121)
+docker-unavailable = ✗ Docker indisponible
+ssh-error = { $node } ({ $ip }): ✗ Erreur SSH : { $error }
+task-join-error = ✗ Erreur de jonction de tâche : { $error }

locales/it/main.ftl

@@ -0,0 +1,13 @@
+cluster-not-found = Cluster "{ $name }" non trovato
+nccl-config-missing = Configurazione NCCL non trovata
+cluster-auto-fail = Impossibile selezionare un cluster adatto
+cluster-selected = ✅ Cluster selezionato automaticamente: { $name } ({ $nodes } nodi)
+container-log-header = 📜 Ultimi log del contenitore:
+cluster-stopping = 🛑 Arresto del cluster '{ $name }'...
+cluster-all-stopped = ✅ Tutti i contenitori arrestati.
+cluster-section = === Cluster: { $name } ===
+container-count = Totale contenitori: { $count }
+no-sm121-containers = (nessun contenitore sm121)
+docker-unavailable = ✗ Docker non disponibile
+ssh-error = { $node } ({ $ip }): ✗ Errore SSH: { $error }
+task-join-error = ✗ Errore di unione attività: { $error }