Add oxlint config and fix unicorn/no-array-sort violation

Promote unicorn/no-array-sort to error in oxlint.json and replace
[...teams].sort() with teams.toSorted() in discord.ts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/services/discord.ts

@@ -208,7 +208,7 @@ export async function sendDraftOrderNotification({
       ? `Draft Order Manually Set — ${leagueName}`
       : `Draft Order Randomized — ${leagueName}`;
 
-  const sorted = [...teams].sort((a, b) => a.position - b.position);
+  const sorted = teams.toSorted((a, b) => a.position - b.position);
   let description = sorted
     .map((t) => {
       const teamLabel = escapeMarkdown(t.name);

oxlint.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "unicorn/no-array-sort": "error"
+  }
+}