ci(release): add workflow_dispatch trigger as fallback (#261)

GitHub occasionally drops tag push events; this adds a manual trigger
so we can re-run the release job against any tag ref without having to
delete and re-push the tag.

.github/workflows/release.yml

@@ -4,6 +4,7 @@ on:
   push:
     tags:
       - "v*"
+  workflow_dispatch:
 
 permissions:
   contents: write