fix(client-slack): implement Media type properties in message attachments #1384

[AIFlowML]

Description

This PR fixes issue #1384 by properly implementing the Media type interface for message attachments in the Slack client.

Changes

• Updated the content object creation in messages.ts to include all required Media type properties
• Fixed Jest configuration to support ES modules

Testing

• All tests passing (11/11)
• Verified proper implementation of Media type interface with required properties:
  • id
  • url
  • title
  • source
  • description
  • text

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Related Issues

Fixes #1384