fix(ci): avoid duplicate builds on release workflow (#13)

Only build assets on prereleased event to prevent redundant builds
when converting pre-release to release. The publish-npm job already
has its own condition and will only run on released event.

Co-authored-by: Claude <noreply@anthropic.com>

Author: jorben

.github/workflows/release.yml

@@ -9,6 +9,8 @@ permissions:
 
 jobs:
   build:
+    # Only build assets on prereleased to avoid duplicate builds
+    if: github.event.action == 'prereleased'
     strategy:
       matrix:
         include: