ux: add confirmation prompts for irreversible operations

[owenwahlgren]

Description

Only keys delete has a confirmation prompt. Other high-stakes operations proceed without confirmation.

Operations missing confirmation

1. subnet convert-l1 - irreversible conversion, should always confirm
2. validator add - locks significant funds for a minimum duration
3. Large transfers - transfers above a configurable threshold

Current behavior

# This irreversible operation runs immediately with no confirmation
platform subnet convert-l1 --subnet-id ... --chain-id ... --mock-validator

Expected behavior

Converting subnet 2QYfFcfZ9... to L1. This operation is IRREVERSIBLE.
Type 'yes' to confirm: 

Severity

Medium - safety improvement for production use

Source

CLI UX audit (2026-02-09)