[Container] When a user authors Background Image in a container component. Dynamic Media URL is not used rather its using /content/dam path

## Feature Request

**Is your feature request related to a problem? Please describe.**
When an author sets a “Background Image” on the Container component, the published markup continues to reference the original /content/dam/... path instead of resolving to the Dynamic Media URL. As a result, authors cannot leverage Dynamic Media features (auto-cropping, responsive breakpoints, etc.) for container backgrounds—AEM always renders the static DAM URL even when a Dynamic Media URL is available.

Start by tracing the Container component's Background Image handling from authoring to the published markup, focusing on where the /content/dam path is selected instead of a Dynamic Media URL. Done means a configured Dynamic Media background resolves to its Dynamic Media URL in published output while existing static DAM behavior remains intact.

Written by the indexing model from the issue text.