Bug Fix: keep local changes commit controls visible on short windows

[w0lflow]

Description

Problem

The commit editor and commit action buttons disappear from the Local Changes page when the application window is resized to a shorter height.

This happens because the diff panel has a fixed minimum height of 400
pixels, while the commit message editor also reserves a fixed height of 128
pixels. When the available vertical space becomes smaller than the combined
layout requirements, the commit editor and action row are pushed outside the
visible area.

Solution

Make the right side of the Local Changes page responsive to the available
height:

• Use a 3* row for the diff panel and a 1* row for the commit message
  editor.
• Reduce the minimum height of both sections to 100 pixels.
• Configure the splitter to resize the diff and commit message sections
  together.
• Preserve the commit options and action buttons at the bottom of the page.

This keeps the commit controls accessible when the application window is
vertically constrained while preserving the existing layout behavior at
larger sizes.

Validation

video with bug

bug.mp4

video without bug

without-bug.mp4

[love-linger]

• Use a 3* row for the diff panel and a 1* row for the commit message editor.
• Reduce the minimum height of both sections to 100 pixels.
• Configure the splitter to resize the diff and commit message sections together.
• Preserve the commit options and action buttons at the bottom of the page.

Please remove all other changes except the 2nd one. The main principle for this page is we should leave more space to the diff viewer rather than the commit message editor. And if they want a larger commit message editor, they can use the splitter to resize it.

[w0lflow]

it's done

I've tested again