feat(amneziawg): remove the vestigial routeThroughXray toggle from the UI

Hard cutover, part 4: the embedded path has no opt-in gate for Xray
routing at all (every peer's traffic already goes through Xray's own
SOCKS5 relay unconditionally -- see xray.go's injectAmneziawgnetSocks), so
a toggle that no longer does anything would just confuse admins. Removed
from the form (amneziawg.tsx), the per-protocol Zod schema and its
new-inbound default, and the routeThroughXray/routeThroughXrayHint i18n
strings across all 13 locales.

The Go-side field stays (see internal/amneziawg's ServerSettings/Instance,
already annotated as vestigial in the previous commit) for backward
compatibility with existing stored settings -- z.object's default
unknown-key stripping means the form simply drops it from an existing
inbound's settings on its next save, no migration needed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

internal/web/translation/es-ES.json

@@ -1654,8 +1654,6 @@
         "ipv6SubnetHint": "p. ej. fd86:ea04:1115::/64. Obligatorio cuando IPv6 está habilitado.",
         "ipv6ExternalInterface": "Interfaz externa IPv6",
         "ipv6ExternalInterfaceHint": "Interfaz de red del host para las entradas de proxy NDP. Déjalo vacío para reutilizar la interfaz externa.",
-        "routeThroughXray": "Enrutar a través de Xray",
-        "routeThroughXrayHint": "Desactivado de forma predeterminada: el túnel no depende de Xray en absoluto. Al activarlo, el tráfico de cada cliente se redirige al puente Xray propio de esta entrada, y la salida real se elige desde la página de Enrutamiento igual que con cualquier otro protocolo.",
         "obfuscation": "Parámetros de ofuscación",
         "regenerateObfuscation": "Regenerar",
         "jc": "Jc (cantidad de paquetes basura)",