conf(versions): update backend image tag to v2.38.0; bump plumber cha…

[thomasboni]

…rt version to 1.3.3

[cursor]

PR Summary

Low Risk
Config-only changes that just bump chart/app versions and the deployed backend/worker image tag; risk is limited to any behavior changes introduced by backend v2.38.0 at deploy time.

Overview
Updates the Plumber Helm chart release metadata (Chart.yaml) from 1.3.2 to 1.3.3.

Bumps the backend image tag from v2.37.1 to v2.38.0 for both backend and worker in values.yaml, and aligns versions.env to BACKEND_IMAGE_TAG=v2.38.0.

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