Add workflow_dispatch and concurrency guard to prevent checksum races

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: LuckyNoS7evin

.github/workflows/publish.yml

@@ -3,6 +3,11 @@ name: Publish Plugin
 on:
   push:
     branches: [main]
+  workflow_dispatch:
+
+concurrency:
+  group: publish
+  cancel-in-progress: false
 
 permissions:
   contents: write