chore: bootstrap from 2026.8.2.1

The package is published and verified on both mirrors, so the self-host
build can start from it. Deliberately a separate change from the version
bump: moving this pin before the release exists sends every CI job to
install a version that is not there yet.

Author: Sunrisepeak

.xlings.json

@@ -1,5 +1,5 @@
 {
   "workspace": {
-    "mcpp": "2026.8.1.1"
+    "mcpp": "2026.8.2.1"
   }
 }