refactor(inbounds): cleaner network tags and cover Mixed/Tunnel + client form select polish

The InboundList protocol column had a few rough edges: raw transports
rendered with mixed casing (TCP vs ws vs grpc), WireGuard never got a
network tag at all, and Mixed/Tunnel rows had no L4 indication even
though they listen on tcp/udp combinations through their own settings
keys (settings.udp for Mixed, settings.allowedNetwork for Tunnel).

Normalise the column: a small networkLabel helper upper-cases every
known transport (so TCP / UDP / KCP / QUIC / WS / GRPC / HTTP all
share the same visual weight, with HTTPUpgrade / SplitHTTP / XHTTP
keeping a touch of casing for readability). Add an extra UDP tag
beside KCP / QUIC so the user sees the underlying L4 without having
to know each transport's wire shape. Add isTunnel to the dbinbound
model and per-protocol branches for Mixed (TCP / TCP,UDP) and Tunnel
(reads settings.allowedNetwork the same shape Shadowsocks uses for
settings.network).

Also polish the attached-inbounds Select in the client form: open
upwards (placement="topLeft") with a 220px listHeight and
maxTagCount="responsive" so a long selection doesn't push the modal's
Save button below the viewport.

frontend/src/models/dbinbound.ts

@@ -155,6 +155,10 @@ export class DBInbound {
         return this.protocol === Protocols.HYSTERIA;
     }
 
+    get isTunnel() {
+        return this.protocol === Protocols.TUNNEL;
+    }
+
     get address(): string {
         let address = location.hostname;
         if (!ObjectUtil.isEmpty(this.listen) && this.listen !== "0.0.0.0") {