[FEATURE] Limit batch work to only use subscription tokens, and not extra tokens

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

When starting batch work I don't want them to only consume tokens from the subscription, and not any extra tokens purchased that I want to use only for interactive work.

This would work nicely together with https://github.com/anthropics/claude-code/issues/39234

Proposed Solution

Allow limiting batch work to only use subscription tokens,

• globally for all batch work in the user settings
• for a single batch job in the batch job command line

Alternative Solutions

_No response_

Priority

High - Significant impact on productivity

Feature Category

CLI commands and flags

Use Case Example

1. I am working on a geometry package
2. I have created a project plan with multiple work items that are relatively independent
3. I also have work items that needs to be explored interactively before including in project plan (a pre-study)
4. I want to start 2-3 batch jobs using at most 25% of the subscriptions tokens
5. I use remaining 25% or 50% for interactive work
6. If the interactive work needs more tokens, then I can purchase these knowing that the batch work will not use them

Additional Context

_No response_