feat(sub): make the host "Mihomo X25519" switch drop ML-KEM (#6803)

The per-host Mihomo X25519 switch has been stored since managed hosts landed,
but no renderer read it, while every REALITY proxy was forced to
support-x25519mlkem768: true. On some networks DPI drops the second segment of
an ML-KEM ClientHello and blackholes the server for that client. A host with the
switch on now gets support-x25519mlkem768: false and no ML-KEM hint in its vless
link; switches saved while they had no effect are cleared once, so upgrading
does not silently change existing subscriptions.

A REALITY host's fingerprint now reaches the Clash and JSON outputs, and every
host endpoint gets its own deep copy of the stream, so one host's blank SNI,
fingerprint, Host header or path no longer inherits another host's value.

internal/web/translation/es-ES.json

@@ -2383,6 +2383,7 @@
         "serverDescription": "Nota opcional que se muestra bajo las notas.",
         "allowInsecure": "Omitir la verificación del certificado TLS (allowInsecure / skip-cert-verify).",
         "vlessRoute": "Un único valor de ruta VLESS (0-65535) incrustado en el UUID, p. ej. 443. Déjalo en blanco para ninguno.",
+        "mihomoX25519": "Solo Mihomo: usa un saludo REALITY con X25519 simple, sin ML-KEM (support-x25519mlkem768: false). Para servidores con Xray-core anterior a 26.9.8, que no exigen ML-KEM.",
         "remark": "Una etiqueta simple para este host. Se muestra como nombre de la configuración solo cuando el inbound no tiene notas propias."
       },
       "remarkVars": {