Remove a bot

[CarsonL15]

As an admin, I want to remove a decommissioned bot from the system, so that retired robots no longer appear in the active fleet.

Acceptance criteria:

• A delete control is available on each bot row or in the bot detail view
• A confirmation prompt protects against accidental deletion
• Confirming calls DELETE /api/bots/{id}
• The bot disappears from the list on success
• If the API rejects deletion (for example, the bot has an active order), the error is shown to the admin