fix: skip Azure deploy when token is missing (closes #79)

Dependabot PRs don't have access to repository secrets, causing the
Azure Static Web Apps deploy step to fail. Adding
skip_deploy_on_missing_secrets: true allows the job to pass gracefully.

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

Author: chrisjwalk-bot

.github/workflows/preview.yml

@@ -47,6 +47,7 @@ jobs:
           action: upload
           app_location: dist/apps/web-app/browser
           skip_app_build: true
+          skip_deploy_on_missing_secrets: true
 
   close_preview:
     if: github.event.action == 'closed'