wrap the connection form in a <form> so enter submits

the url and api key fields sat in a div, so pressing enter did nothing
and the save button was the only way in. same fix as gitea's connection
screen: submit is now onSubmit with preventDefault, and disconnect is
marked type="button" so it can't submit the form.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

web/SoulseekConnection.tsx

@@ -52,7 +52,8 @@ export const SoulseekConnection = () => {
     setApiKey('');
   }, [connection?.id]);
 
-  const submit = async () => {
+  const submit = async (ev: React.FormEvent) => {
+    ev.preventDefault();
     setError('');
     try {
       await save.mutateAsync({ url: url.trim(), apiKey: apiKey.trim() });
@@ -98,7 +99,7 @@ export const SoulseekConnection = () => {
 
         {connection && <StatusRow connection={connection} health={health} />}
 
-        <div className="flex flex-col gap-4 rounded-xl border p-4">
+        <form onSubmit={submit} className="flex flex-col gap-4 rounded-xl border p-4">
           <label className="flex flex-col gap-1.5">
             <span className="text-xs font-medium">Server URL</span>
             <Input
@@ -134,21 +135,21 @@ export const SoulseekConnection = () => {
 
           <div className="flex items-center gap-2">
             <Button
+              type="submit"
               size="sm"
-              onClick={submit}
               disabled={!url.trim() || (!apiKey.trim() && !connection?.hasSecret) || save.isPending}
             >
               {save.isPending && <Loader2 className="mr-2 h-3.5 w-3.5 animate-spin" />}
               {connection ? 'Save' : 'Connect'}
             </Button>
             {connection && (
-              <Button size="sm" variant="ghost" onClick={remove} disabled={forget.isPending}>
+              <Button type="button" size="sm" variant="ghost" onClick={remove} disabled={forget.isPending}>
                 <Trash2 className="mr-2 h-3.5 w-3.5" />
                 Disconnect
               </Button>
             )}
           </div>
-        </div>
+        </form>
       </div>
     </div>
   );