[FEATURE] Config setting to disable ultra plan

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Sometimes ultra plan fires. I never intend or want it to and it's hard to stop and appears to be expensive and a security risk. I would like to be able to add something to stop it ever being offered or firing.

I have searched and you seem to close every issue where someone requests it. So I don't believe there is an open issue requesting this. If there is, I couldn't find it.

Proposed Solution

A new key in settings.json e.g.

"ultraplan": "never"

or

"ultraplan": "disable"

Alternative Solutions

1. A different key that stops it ever bring offered.
2. Disable it everywhere for everyone

Priority

High - Significant impact on productivity

Feature Category

Interactive mode (TUI)

Use Case Example

I talk to Claude in plan mode.

I try to exit plan mode, usually saying "No, we need to discuss more"

Ultraplan starts, possibly because you change the options too often or possibly a bug.

Additional Context

_No response_