fix(finalmask): hop client UDP through the udphop mask

xray-core 26.9.9 dropped finalmask.quicParams.udpHop for the client-only
"udphop" UDP mask {mode, interval, remoteIPs, remotePorts}. The panel kept
writing the old key, so hysteria/xhttp outbounds and JSON-subscription
clients silently stopped hopping ports.

An inbound keeps quicParams.udpHop: it is panel metadata advertised as the
link's mport, and a udphop mask on a listener fails with "udphop: client
only". The conversion (maskcompat.UpgradeLegacyUDPHop, intervalRemote mode)
runs only where a client config is produced:

- UDPHopClientMaskFix seeder over hosts, sub-JSON finalmask, cached
  outbound-subscription outbounds and template outbounds (never inbounds);
- GetXrayConfig heals template outbounds at build time;
- the JSON subscription upgrades each generated client stream;
- the Go and frontend link importers upgrade a legacy fm= param.

The finalmask editor gains a side prop: the client side lifts the dead key
on mount and offers a udphop mask editor (also for xhttp's HTTP/3 dial);
the inbound side keeps the UDP Hop switch, labelled as advertised.

frontend/src/lib/xray/forms/fields/FinalMaskField.tsx

@@ -10,6 +10,7 @@ interface FinalMaskFieldProps {
   network: string;
   protocol: string;
   showAll?: boolean;
+  side?: 'server' | 'client';
 }
 
 const EMPTY: FinalMaskStreamSettings = { tcp: [], udp: [] };
@@ -20,6 +21,7 @@ export default function FinalMaskField({
   network,
   protocol,
   showAll,
+  side,
 }: FinalMaskFieldProps) {
   const [form] = Form.useForm();
   const [initial] = useState(() => value ?? EMPTY);
@@ -55,6 +57,7 @@ export default function FinalMaskField({
         protocol={protocol}
         form={form}
         showAll={showAll}
+        side={side}
       />
     </Form>
   );