Sub task/setup the infrastructure and backend interfaces core 555

[irumvanselme]

Fixes

• CORE-555

[sentry]

Bug: The POST handler for model embedding processes is an unimplemented stub that will cause all requests to this endpoint to return a 500 error.
_{Severity: HIGH}

Suggested Fix

Implement the logic for the POSTModelEmbeddingProcessesHandler to correctly handle the creation of model embedding processes. If this feature is not ready for release, either remove the route from the main router in backend/src/index.ts or place it behind a feature flag to prevent access.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: backend/src/modelInfo/embeddingProcesses/POST/index.ts#L6

Potential issue: The POST handler for the `/models/:modelId/embedding-processes` route
is a stub that unconditionally throws `new Error("Not implemented yet")`. This route is
wired into the production router without any feature flag or conditional logic to
prevent access. Consequently, any POST request to this endpoint will be caught by a
generic error handler, resulting in a 500 Internal Server Error response for the client.
The endpoint is effectively broken and will fail for every request.

_{Did we get this right? 👍 / 👎 to inform future reviews.}