feat: ship the .desktop entry in this repo

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, next to Cargo.toml and any unit file the crate ships, and `ccebuild install` deploys it.

Exec drops the hardcoded /home/lsgalante/.local/bin prefix for a bare binary name: ~/.local/bin leads the session PATH and the launcher spawns through `sh -c`, so the name resolves without baking a home directory into the file.

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

 cce-system-interface.desktop | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/cce-system-interface.desktop b/cce-system-interface.desktop
new file mode 100644
index 0000000..f9a00a7
--- /dev/null
+++ b/cce-system-interface.desktop
@@ -0,0 +1,10 @@
+[Desktop Entry]
+Type=Application
+Name=System Interface
+Comment=Power, audio, network, display, and system management
+Exec=cce-system-interface
+Icon=preferences-system
+Categories=Settings;System;
+Keywords=power;audio;network;display;system;brightness;volume;
+StartupNotify=true
+StartupWMClass=cce-system-interface