Shell terminal ignores the light/dark theme setting

Description Switching the UI between light and dark mode does not affect the shell terminal. The terminal always renders with a dark background, even when the rest of the UI is in light mode. Version: CloudCLI UI v1.37.3

Cause In dist/assets/index-*.js the xterm options constant carries a hardcoded theme object:

theme:{background:"#1e1e1e",foreground:"#d4d4d4",cursor:"#ffffff",...}

This object is passed to new Terminal(...) as-is. The theme toggle only adds/removes the dark class on document.documentElement, which the terminal never reads. Settings only expose "Editor Theme" for the code editor, there is no terminal equivalent.

Overriding via CSS is not an option either, since the WebGL addon renders glyphs to a canvas.

Same class of bug as #787 (code editor theme not syncing), which was fixed for CodeMirror. The shell terminal still has it.

To Reproduce Steps to reproduce the behavior:

1. Open a session and switch to the Shell tab.
2. Set the UI to light mode in Settings.
3. The terminal background stays #1e1e1e.

Expected behavior The terminal theme follows the app theme

Desktop:

• OS: macOS 26.6.2
• Browser Chrome
• Version 153.0.8010.12 (Official Build) (arm64)

Additional context For users with low vision this is an accessibility problem, not a preference. Which contrast polarity is readable is individual: some people need dark text on a light background, others the reverse, and the theme toggle is how they set that. A surface that ignores the toggle takes that choice away for the one part of the app where the agent's output actually appears.