fix(clients): hide WireGuard config after detaching the WG inbound

The client info and QR modals rendered a WireGuard config whenever the
client still carried leftover WG key material (privateKey / publicKey /
allowedIPs / preSharedKey / keepAlive), regardless of whether a WireGuard
inbound was actually attached. After detaching the WG inbound the config
kept showing, built with an empty endpoint port and public key.

Gate wgConfigText on an attached WireGuard inbound (wgInbound) being
present, not just isWireguardClient(client), in both ClientInfoModal and
ClientQrModal.

Also rename the i18n key pages.clients.conf -> config and add the missing
pages.clients keys (wireguardConfig, config, bulkFlow, bulkFlowNoChange,
bulkFlowDisable) to all 12 non-English locales so each one matches en-US.

internal/web/translation/es-ES.json

@@ -718,6 +718,8 @@
       "tabBasics": "Básico",
       "tabCredentials": "Credenciales",
       "tabLinks": "Enlaces",
+      "wireguardConfig": "Configuración de WireGuard",
+      "config": "Configuración",
       "linksHint": "Añade enlaces de terceros y URLs de suscripción remotas para incluirlos en la suscripción de este cliente.",
       "addExternalLink": "Añadir enlace externo",
       "addExternalSubscription": "Añadir suscripción externa",
@@ -871,6 +873,9 @@
       "bulkAdjustNothing": "Establece días o tráfico antes de aplicar.",
       "addDays": "Añadir días",
       "addTrafficGB": "Añadir tráfico (GB)",
+      "bulkFlow": "Establecer flow",
+      "bulkFlowNoChange": "Sin cambios",
+      "bulkFlowDisable": "Desactivar (borrar flow)",
       "delDepleted": "Eliminar agotados",
       "delDepletedConfirmTitle": "¿Eliminar clientes agotados?",
       "delDepletedConfirmContent": "Elimina todos los clientes con cuota agotada o expirados. No se puede deshacer.",