guis: add Git Agent

[adoin]

Changes

• Add Git Agent to the GUI client directory for Windows, Mac, and Linux.
• Add 588 x 332 and 1176 x 664 PNG thumbnails of the actual application.

Context

I maintain Git Agent, a native desktop Git
client built with Rust and egui. It provides a workspace and diff viewer, commit
history, branch management, and a three-way merge editor with optional AI-assisted
merge suggestions.

Version 1.4.0 includes
Windows, universal macOS, and Debian/Ubuntu amd64 installation packages. The
application is free to download, with voluntary donations. Optional AI use
requires the user's own provider configuration; provider charges may apply.

The project's license is
Apache License 2.0 subject to Commons Clause License Condition v1.0. The listing
states both parts; this is source-available software, not unmodified Apache 2.0
or an OSI-approved open-source license. Internal business use is permitted;
the Commons Clause restriction on "Sell" applies. The licensing files were added
to the project after v1.4.0; existing release assets have not been rebuilt or retagged.

The images show the actual history view in a test repository. They are scaled
proportionally and padded to the directory's required aspect ratio, without
cropping, redrawing, or changing application content.

Project website: https://git-agent.emssion.com/

Validation

• Checked required listing fields and the next available order value.
• Verified both PNG dimensions, aspect ratio, and referenced image path.
• Reviewed the generated thumbnails and ran git diff --check.
• The complete Hugo build and upstream browser suite have not been run locally.