Add workflow_dispatch trigger to deploy workflow

Enables manual triggering of the deploy workflow from the GitHub Actions UI,
in addition to the existing push-to-main trigger.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: rasca

.github/workflows/deploy.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+  workflow_dispatch:
 
 jobs:
   deploy: