fix(tui): prevent sidebar height from overflowing.

[IdrisGit]

What does this PR do?

• fixes height of the sidebar to "100%", preventing sidebar from overflowing, specially on smaller screens.
• this issue surfaced after this PR (tui: add overlay sidebar for narrow screens to improve mobile experience #7288) as it converts sidebar to an overlay for smaller screens

How did you verify your code works?

• tested fixe against the latest version (1.1.27) by following the steps in (tui) sidebar overflowing out of the viewport at smaller widths/size #9686
• fixed version screenshots attached below

window fullscreen:

window normal/half:

fixes #9686

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Related PR Found:

PR #7988: fix(ui): improve sidebar accessibility and responsiveness on zoom and small screens
#7988

Why it might be related:

• Both PRs address sidebar responsiveness issues on small screens
• PR fix(ui): improve sidebar accessibility and responsiveness on zoom and small screens #7988 appears to handle sidebar accessibility and responsiveness, which may overlap with the height overflow fix in the current PR fix(tui): prevent sidebar height from overflowing. #9689
• Both deal with sidebar behavior on smaller screens/mobile viewports

Note: The current PR mentions that the overflow issue "surfaced after PR #7288" which converted the sidebar to an overlay for smaller screens. PR #7988 (from your search results) also addresses sidebar responsiveness on small screens, so there could be related changes or overlapping scope.