[Feature] 希望添加分屏内部拖拽切换功能

[misakajolno]

Problem / pain point — 现在的痛点

比如当前是三分屏，有时想把最左侧的分屏拖拽到最右侧使用，当前无法这样操作

Proposed solution — 希望的做法

希望可以灵活的切换各分屏的位置
还有一点，从二分屏到三分屏时，会变为左侧分屏占50%，右侧两个分屏平分剩下的50%，如果可以改为三平分各占33%就更好了

Alternatives considered — 现在的替代办法

No response

Platform / 平台

Windows

Related area / 相关范围

Tabs / splits / session restore / window size — 标签页、分屏、会话恢复、窗口尺寸

How important is this to you? / 对你有多重要

Nice to have / 有更好

Before submitting / 提交前确认

• I searched existing issues for similar requests / 已搜索，无重复

[WilliamWang1721]

Implementation remains in PR #458. Current product head is 3e827fa2947e76259ae4d96d39992ede68bf0a19.

Lint, architecture and PR size checks pass. The native Ubuntu run now passes drag activation/cancellation, but still fails the leaf-order exchange assertion at native_tests.rs:146. The confirmed target-policy mismatch is being corrected in an isolated worktree; the original assertions remain intact. Exact-head Windows mouse/keyboard/live-PTY evidence is running at https://github.com/WilliamWang1721/pebrel/actions/runs/37117391896.

This is still a draft requiring successful native validation and maintainer review; no resolution or merge is claimed.