[codex] Add scrolling column fullscreen and workspace ordering commands

[corpooo]

Summary

This PR adds scrolling column fullscreen commands, workspace ordering commands, and a within-gaps option for scrolling column fullscreen.

Changes

• add scrolling-layout support for fullscreening the selected column and keeping fullscreen state attached to the affected column during layout operations
• add workspace ordering commands and wire them through the controller and CLI
• add configuration and default settings for the new scrolling fullscreen behavior
• add a within-gaps mode so column fullscreen can use the tiling area instead of expanding edge to edge

Validation

• cargo test --lib scrolling -- --nocapture