test(i18n): add pull_request trigger for CI testing

Temporary change to test workflow in PR CI.
Will be reverted after testing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/workflows/translate-i18n-claude.yml

@@ -5,6 +5,10 @@ on:
     branches: [main]
     paths:
       - 'web/i18n/en-US/*.json'
+  pull_request:
+    branches: [main]
+    paths:
+      - '.github/workflows/translate-i18n-claude.yml'
   workflow_dispatch:
     inputs:
       files: