fix: chain dropIndex before createIndex on ap_muted to prevent race condition

The non-async init() fired dropIndex and createIndex concurrently,
causing MongoDB to abort the index build (IndexBuildAborted error 276).
Chain createIndex via .then() so it runs after the drop completes.

Confab-Link: http://localhost:8080/sessions/e9d666ac-3c90-4298-9e92-9ac9d142bc06

index.js

@@ -1000,18 +1000,27 @@ export default class ActivityPubEndpoint {
         );
       }
 
-      // Drop non-sparse indexes if they exist (created by earlier versions),
-      // then recreate with sparse:true so multiple null values are allowed.
-      this._collections.ap_muted.dropIndex("url_1").catch(() => {});
-      this._collections.ap_muted.dropIndex("keyword_1").catch(() => {});
+      // Muted collection — sparse unique indexes (allow multiple null values)
+      this._collections.ap_muted
+        .dropIndex("url_1")
+        .catch(() => {})
+        .then(() =>
           this._collections.ap_muted.createIndex(
             { url: 1 },
             { unique: true, sparse: true, background: true },
-      );
+          ),
+        )
+        .catch(() => {});
+      this._collections.ap_muted
+        .dropIndex("keyword_1")
+        .catch(() => {})
+        .then(() =>
           this._collections.ap_muted.createIndex(
             { keyword: 1 },
             { unique: true, sparse: true, background: true },
-      );
+          ),
+        )
+        .catch(() => {});
 
       this._collections.ap_blocked.createIndex(
         { url: 1 },

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@rmdes/indiekit-endpoint-activitypub",
-  "version": "2.4.0",
+  "version": "2.4.1",
   "description": "ActivityPub federation endpoint for Indiekit via Fedify. Adds full fediverse support: actor, inbox, outbox, followers, following, syndication, and Mastodon migration.",
   "keywords": [
     "indiekit",