Reuse Canvas SDC components when applying SDC Entity Mapping

Problem/Motivation

SDC Entity Mapping currently proves that structured field-to-prop connections can be reused, but the Canvas integration path should better reflect that these mappings are enhancing an existing SDC rather than defining an entirely separate kind of component.

The goal here is to reuse the existing Canvas SDC component flow and allow SDC Entity Mapping to plug into that flow, instead of representing each mapped variant as its own separate Canvas component entry.

This keeps the experience centered on the original SDC while allowing saved field-linking presets to be applied where useful.

Steps to reproduce

1. Create an SDC that is available in Canvas.
2. Create an SDC Entity Mapping for that same component.
3. Integrate the mapping into Canvas.
4. Observe that the mapping is treated as its own Canvas component path rather than reusing the existing SDC component flow.

Proposed resolution

Adjust the Canvas integration so that SDC Entity Mapping reuses the existing Canvas SDC component.

The intended flow is:

1. An editor selects the base SDC component in Canvas.
2. Canvas allows the editor to populate props manually as usual.
3. If a mapping to that SDC component exists, Canvas will also allow the editor to choose a SDC Entity Mapping.
4. If selected, the mapping provides the saved field-to-prop connections for the chosen entity context.

This frames SDC Entity Mapping as reusable field-linking logic applied to an SDC instance, rather than as a separate component definition.

Remaining tasks

• Define the integration points needed for Canvas to detect and offer applicable SDC Entity Mappings for a selected SDC.
• Decide how and when the mapping-selection UI should appear.
• Decide how manual prop entry and mapped values should coexist.
• Implement the updated Canvas integration.

User interface changes

Canvas would continue to present the existing SDC component.

Where applicable, Canvas would also offer a way to apply an SDC Entity Mapping to that selected component rather than requiring a separate mapped-component entry.

API changes

None defined yet.

This issue is focused on integration and UX direction for reusing Canvas SDC components.

Data model changes

None required.

The existing SDC Entity Mapping config entities can continue to represent saved field-to-prop connections.