[FEATURE] Add input validation to installer

[youngcoder45]

Problem / motivation

Prevent invalid user inputs during installation.

Installer wipes disk → dangerous if wrong input is given.

Proposed solution

1. Validate disk selection
2. Add confirmation step
3. Prevent accidental formatting

Alternatives considered

• Installer warns user before destructive actions
• Invalid input handled safely

Files:

• scripts/
• installer logic