feat: ship the .desktop entry in this repo, with a working Icon

The entry lived only in ~/.local/share/applications, hand-written and unversioned — the workspace root is not a git repo, so nothing written there survives a fresh clone. It now sits at the crate root and `ccebuild install` deploys it.

Two absolute paths are gone. Exec becomes a bare binary name (~/.local/bin leads the session PATH, and the launcher spawns through `sh -c`). Icon pointed at /home/lsgalante/Dropbox/Clear/clear-icons/png/star.png, which no longer exists — the theme moved out from under it and nothing reported the dangling reference. It is now a plain icon name, which is what the spec asks for and what every other entry here uses.

Co-Authored-By: Claude <[email protected]>

 cce-test-interface.desktop | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/cce-test-interface.desktop b/cce-test-interface.desktop
new file mode 100644
index 0000000..a748737
--- /dev/null
+++ b/cce-test-interface.desktop
@@ -0,0 +1,9 @@
+[Desktop Entry]
+Type=Application
+Name=Clear Test Interface
+Comment=GUI diagnostic and verification window for Clear desktop environment
+Exec=cce-test-interface
+Icon=cce-test-interface
+Terminal=false
+Categories=Utility;Development;
+StartupNotify=true