[FEATURE] overriding borders on plan mode with output style

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

The borders on plan mode are incredibly annoying and make copying anything spanning multiple lines painful within the plan mode borders / pane. It's a _pane_ in the butt. Every line copied has | | at the beginning and end of the line that must be manually removed.

I tried creating an output style that says not to do this but those instructions are ignored.

─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ Ready to code?                                                                                                                                                                                          │
│                                                                                                                                                                                                         │
│ Here is Claude's plan:                                                                                                                                                                                  │
│ ╭─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮ │
│ │ Plan:  Ignore Output Style

Proposed Solution

The plan mode should respect output style if defined.

Alternative Solutions

Configurable option.

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)

Use Case Example

_No response_

Additional Context

_No response_