UI Integration with Existing MCP Server

As a user, I want my messages to be sent to an AI assistant so that I can receive responses in the chat interface.

Acceptance Criteria:
- User messages are sent from the UI to the MCP server
- UI does not expose AWS or Bedrock credentials
- Assistant responses are siplayed in the chat
- Multiple back-and-forth  messages are supported.
- Backend errors do not crash the UI.