[FEATURE] Mods: keep the Pane close mark (×) and the band's [-] off the terminal's last column

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

With Claude Code 2.1.287 in the fullscreen layout, two marks drawn by the engine for plugin UI sit in the terminal's last column (position: absolute; right: 0):

• the close mark (×) of a docked plugin Pane;
• the [-] collapse mark of the AbovePrompt band.

Some terminal hosts draw their own UI on that edge. I use Herdr on Windows, and its edge UI overlaps both marks, so they are hard to click and look broken. A plugin cannot move them, because the engine draws them.

Proposed Solution

Keep a one-column inset on the right for engine-drawn marks of plugin UI, or let the person set it (for example a setting such as tui.rightInset). The prompt box and the footer already keep a small margin from the edge.

Alternative Solutions

None from a plugin: both marks are engine-drawn and absolutely positioned at right: 0.

Priority

Low - Nice to have

Feature Category

Interactive mode (TUI)

Use Case Example

1. Run Claude Code fullscreen inside a terminal host that draws its own UI on the right edge.
2. Open a docked plugin pane (for example a mod's /despachos panel) or show a mod's band above the prompt.
3. The × or [-] sits under the host's edge UI.

Additional Context

Related: #98986 (the band's [-] collapse control).