Add a confirm dialog before deleting an endpoint/dataset

[prat3ik]

Add a confirmation dialog before deleting a Chatbot Endpoint (and Dataset) to prevent accidental data loss.

Where: client/ — the endpoint list / dataset list delete actions.

Details:

• Show a small "Are you sure?" confirm before calling the delete API.
• Reuse any existing dialog/confirm pattern in the codebase if present.

Acceptance:

• Deleting requires explicit confirmation; cancel does nothing.