Fix: hysteria link gen crashes when echConfigList is a string (#4064)

`genHysteriaLink` was calling `.join(',')` on
`this.stream.tls.settings.echConfigList`, but that field is bound to an
`<a-input>` (single-line string) in `tls_settings.html` and defaults to
`''` in `TlsStreamSettings.Settings`. Calling `.join()` on a string
throws `TypeError: echConfigList.join is not a function`, which breaks
the Info / QR buttons for every hysteria / hysteria2 inbound.

All three sibling link generators (`genVmessLink`, `genVlessLink`,
`genTrojanLink`) already pass the value directly:

    params.set("ech", this.stream.tls.settings.echConfigList)

`URLSearchParams.set` will stringify arrays with `,` on its own, so the
same one-liner works for both string and array inputs. Align
`genHysteriaLink` with the other three.

Fixes #4063

Co-authored-by: pwnnex <[email protected]>

web/assets/js/model/inbound.js

@@ -1827,7 +1827,7 @@ class Inbound extends XrayCommonClass {
         if (this.stream.tls.settings.fingerprint?.length > 0) params.set("fp", this.stream.tls.settings.fingerprint);
         if (this.stream.tls.alpn?.length > 0) params.set("alpn", this.stream.tls.alpn);
         if (this.stream.tls.settings.allowInsecure) params.set("insecure", "1");
-        if (this.stream.tls.settings.echConfigList?.length > 0) params.set("ech", this.stream.tls.settings.echConfigList.join(','));
+        if (this.stream.tls.settings.echConfigList?.length > 0) params.set("ech", this.stream.tls.settings.echConfigList);
         if (this.stream.tls.sni?.length > 0) params.set("sni", this.stream.tls.sni);
 
         const udpMasks = this.stream?.finalmask?.udp;