[Feature]: Create record push response message with error field

[akijakya]

Problem Statement

Currently the gRPC messages around pushing a record to the server are very basic. The push message only contains a record object and the response only contains a CID. There is no room for receiving detailed error messages if a push failed without terminating the entire stream.

The current implementation terminates the stream when validation fails, which prevents batch operations from processing remaining records after a single failure.

Proposed Solution

Add a PushResponse message (similar to PushReferrerResponse) that can return either:
• Success: CID in record_ref field
• Failure: Error details in error_message field
This enables batch operations to continue processing even if individual records fail validation.

Also switch back to stream pushing in importer and handle error messages so a failure doesn't make the import process to hang.

Alternatives Considered

No response

Additional Context

No response

Checklist

• I have read the contributing guidelines
• I have verified this does not duplicate an existing feature request

[tkircsi]

This issue relates to #708