[codex] Notify infra-apps after PRE frontend image push

[dmarmon-gesplan]

Summary

• Adds an optional repository_dispatch notification after the PRE frontend image is pushed to ECR.
• Sends event_type deploy-vestimenta-pre to gesplan-idi/infra-apps with component frontend and image_tag sha-GITHUB_SHA.
• Uses the INFRA_APPS_DISPATCH_TOKEN secret and skips notification without failing the image publish if the secret is absent.

Impact

• appVestimenta still only builds and pushes ECR images.
• No Helm, kubectl, Terraform, PRO, or latest tag usage is introduced.

Validation

• git diff --check