use black-circle appicon for macOS

Replaces the transparent-background icons in the macOS asset
catalog with the black-circle variants from assets/logo/. The
64px size is downscaled from the 128px source since the master
set doesn't include that size.

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

.pql/pql-plan.json

@@ -1,5 +1,5 @@
 {
-  "exported_at": "2026-04-26T11:34:32Z",
+  "exported_at": "2026-04-26T11:34:37Z",
   "decisions": [
     {
       "id": "D-1",