ci(workflow): simplify Cloudflare Pages deploy command by removing empty env flag

Removed the --env "" flag from the versions upload command as it's unnecessary.

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

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

Author: ericyangpan

.github/workflows/deploy-preview.yml

@@ -116,7 +116,7 @@ jobs:
         with:
           apiToken: ${{ secrets.CLOUDFLARE_API_TOKEN }}
           accountId: ${{ secrets.CLOUDFLARE_ACCOUNT_ID }}
-          command: versions upload --env "" --preview-alias ${{ steps.preview_meta.outputs.preview_alias }}
+          command: versions upload --preview-alias ${{ steps.preview_meta.outputs.preview_alias }}
 
       - name: Comment Preview URL
         if: github.event_name == 'pull_request'