fix(sub): bake Host VLESS Route into subscription UUIDs

The Host VLESS Route field was stored and shown in the panel but never applied to any generated subscription (raw, JSON, Clash), so the UUID was emitted unmodified (#5655).

Xray reads the route from the UUID's 3rd group (bytes 6-7, net.PortFromBytes) and masks those bytes to zero before authenticating, so a value can be baked into the share/JSON/Clash UUIDs without breaking the user match. A shared applyVlessRoute helper encodes a single 0-65535 value as the 3rd group; empty/invalid/non-UUID input is left unchanged, so legacy data never yields a broken link and no DB migration is needed.

The field was wrongly validated as a multi-segment port spec (that form belongs to the separate server-side routing rule). It is now a single value 0-65535, with frontend validation, link-preview parity (genVlessLink/hostToExternalProxyEntry), hint + error translations across all 13 locales, and tests on every path.

Closes #5655

internal/web/translation/en-US.json

@@ -1032,7 +1032,7 @@
         "nodeGuids": "Pick nodes which resolved from this host. Only visual assignment.",
         "serverDescription": "Optional note shown under the remark.",
         "allowInsecure": "Skip TLS certificate verification (allowInsecure / skip-cert-verify).",
-        "vlessRoute": "Ports/ranges routed via VLESS, e.g. 53,443,1000-2000. Leave blank for none.",
+        "vlessRoute": "Single VLESS route value (0-65535) baked into the UUID, e.g. 443. Leave blank for none.",
         "remark": "A plain label for this host. Shown as the config name only when the inbound has no remark of its own."
       },
       "remarkVars": {
@@ -1082,7 +1082,7 @@
         "update": "Update host",
         "delete": "Delete host",
         "badTag": "Invalid tag",
-        "badVlessRoute": "Use ports/ranges like 53,443,1000-2000"
+        "badVlessRoute": "Enter a single number between 0 and 65535"
       }
     },
     "nodes": {